ORCID Profile
0000-0001-9264-1726
Current Organisation
Julius-Maximilians-Universität Würzburg
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Publisher: American Chemical Society (ACS)
Date: 17-09-2018
DOI: 10.1021/JACS.8B08428
Abstract: The reaction of the tetrahalodiboranes(4) B
Publisher: American Chemical Society (ACS)
Date: 24-01-2013
DOI: 10.1021/JA3110126
Abstract: Room-temperature photolysis of the aminoboryl complex [(OC)(5)Cr═B═N(SiMe(3))(2)] in the presence of a series of mono- or bis(boryl) alkynes bis{bis(dimethylamino)boryl}ethyne, 1-phenyl-2-bis(dimethylamino)borylethyne, and 1-trimethylsilyl-2-bis(dimethylamino)borylethyne led to the isolation of hitherto unknown borylborirenes in resonable yields, that is, [(RC═CR')(μ-BN(SiMe(3))(2))] (7, R = B(NMe(2))(2), R' = Ph 8, R = R' = B(NMe(2))(2) 9, R = B(NMe(2))(2), R' = SiMe(3)). The borirenes were isolated and spectroscopically characterized by multinuclear NMR, IR, and UV/vis spectroscopy, crystallography, and elemental analysis. Reactivity studies of the borirenes demonstrated their behavior toward different Lewis bases. The isolated adducts and the parent borirenes were compared to 1,3-mesityl-2-phenylborirene and its adducts. To gain insight into the electronic structure and to evaluate the influence of the exocyclic groups, Density Functional Theory (DFT) calculations were carried out.
Publisher: Wiley
Date: 06-2017
Abstract: Although the metathesis of metal-boron double bonds with elemental chalcogenides is an established process, no similar reactivity has been observed with element-nitrogen bonds. Such a reaction would provide a new route to iminoborane compounds (RB≡NR'), which have recently experienced renewed synthetic interest. Herein, we present the first observation of M=B/C=N metathesis reactions, which led to the isolation of a stable iminoborane in addition to further iminoborane cycloaddition products.
Publisher: Wiley
Date: 09-12-2015
Abstract: Reaction of the zero-valent platinum complex [Pt(PCy3 )2 ] with SbF3 generates the cationic diplatinum stibenium complex [{(Cy3 P)2 Pt}2 (μ-SbF2 )](+) , the first unsupported metal-only Lewis pair containing an antimony-centered Lewis acid. In contrast, SbCl3 undergoes oxidative addition to [Pt(PCy3 )2 ], resulting in the dihalostibanyl complex trans-[PtCl(SbCl2 )(PCy3 )2 ], the first ex le of oxidative addition of an antimony-halide bond to a transition metal.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4SC00183D
Publisher: Wiley
Date: 12-08-2016
Abstract: A comprehensive study of the reactivity of Lewis bases with dihalodiboranes(4) is presented. Diaryldihalodiboranes provide rearranged monoadducts when treated with cyclic (alkyl)(amino)carbenes, but halide-bridged adducts when treated with a range of pyridyl bases. Alternatively, the combination of diaminodihalodiboranes with strong carbene donors leads to boraborenium salts. The reduction and halide-abstraction reactivity of these adducts was also explored, leading to intramolecular C-H activation and the first 1,2-bis(borenium) dication.
Publisher: Wiley
Date: 20-12-2014
Abstract: The synthesis, reactivity, and properties of boryl-functionalized σ-alkynyl and vinylidene rhodium complexes such as trans-[RhCl(=C=CHBMes2)(PiPr3)2] and trans-[Rh(C≡CBMes2)(IMe)(PiPr3)2] are reported. An equilibrium was found to exist between rhodium vinylidene complexes and the corresponding hydrido σ-alkynyl complexes in solution. The complex trans-[Rh(C≡CBMes2)(IMe)(PiPr3)2] (IMe=1,3-dimethylimidazol-2-ylidene) was found to exhibit solvatochromism and can be quasireversibly oxidized and reduced electrochemically. Density functional calculations were performed to determine the reaction mechanism and to help rationalize the photophysical properties of trans-[Rh(C≡CBMes2)(IMe)(PiPr3)2].
Publisher: Wiley
Date: 27-02-2015
Abstract: A 1,4-dibora-1,3-butadiene iron complex was successfully synthesized through the stoichiometric reaction of an iron bis(borylene) complex with diphenylacetylene. This complex was treated with CO and PMe3 , which led to the formation of an unusual six-membered B2 C3 O ylidic ring bound to both the PMe3 group and zerovalent iron center. The reaction is a very rare ex le of the incorporation of both atoms of CO into a ring system.
Publisher: American Chemical Society (ACS)
Date: 31-01-2013
DOI: 10.1021/JA310895W
Abstract: In early reports, the boron atom of the anionic borido complexes [{(η(5)-C(5)H(4)R)(OC)(2)Mn}(2)B](-) (R = H, Me) showed nucleophilic behavior in the presence of electrophiles such as methyl iodide and group 11 metal chlorides, akin to the ground-breaking boryl lithium of Yamashita and Nozaki. Later, a reaction with the well-known transition metal Lewis base [Pt(PCy(3))(2)] suggested the possibility of boron-centered electrophilicity. In this paper we elucidate a third reactivity profile of the anion, nucleophilic substitution on heavier halides of group 14 metals by a manganese center. Meanwhile, other group 11 halides were found to interact with the boron center, but form structures different from those seen with gold. The basis of the discrimination of the anion between main group and transition metal halides is explored computationally, and the ditopic, ambiphilic reactivity of the anions is discussed.
Publisher: Wiley
Date: 18-07-2018
Abstract: The reaction of a pentamethylcyclopentadienyl-substituted dialane with a variety of Lewis bases results in unexpected disproportionation of the dialane into Al
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7CC09596A
Abstract: A new cyclopentadienyl-containing dialane is prepared and found to undergo dialumination reactions with unsaturated species.
Publisher: Wiley
Date: 27-01-2017
Abstract: A remarkably mild, catalyst-free cyclopropanation reaction is confirmed by low-temperature isolation of a fused bicyclic cyclopropane intermediate. This intermediate is one of two that were isolated and fully characterised in a three-step temperature-controllable reaction cascade.
Publisher: Wiley
Date: 28-07-2008
Publisher: Wiley
Date: 03-12-2021
Abstract: A one‐pot synthesis of a CAAC‐stabilized, unsymmetrical, cyclic diborene was achieved via consecutive two‐electron reduction steps from an adduct of CAAC and B 2 Br 4 (SMe 2 ) 2 . Theoretical studies revealed that this diborene has a considerably smaller HOMO–LUMO gap than those of reported NHC‐ and phosphine‐supported diborenes. Complexation of the diborene with [AuCl(PCy 3 )] afforded two diborene–Au I π complexes, while reaction with DurBH 2 , P 4 and a terminal acetylene led to the cleavage of B−H, P−P, and C−C π bonds, respectively. Thermal rearrangement of the diborene gave an electron‐rich cyclic alkylideneborane, which readily coordinated to Ag I via its B=C double bond.
Publisher: Wiley
Date: 14-04-2018
Abstract: The room-temperature, ambient-pressure reactions of CO
Publisher: American Chemical Society (ACS)
Date: 19-12-2015
DOI: 10.1021/OM501141G
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CC07103H
Abstract: The first cyclic and cis -configured diborenes are prepared in a convenient one-pot synthesis.
Publisher: Wiley
Date: 09-2022
DOI: 10.1002/JCC.26994
Abstract: The development of ligands capable of effectively stabilizing highly reactive main‐group species has led to the experimental realization of a variety of systems with fascinating properties. In this work, we computationally investigate the electronic, structural, energetic, and bonding features of proximity‐enforced group 13–15 homodimers stabilized by a rigid expanded pincer ligand based on the 1,8‐naphthyridine ( napy ) core. We show that the redox‐active naphthyridine diimine (NDI) ligand enables a wide variety of structural motifs and element‐element interaction modes, the latter ranging from isolated, element‐centered lone pairs (e.g., E = Si, Ge) to cases where through‐space π bonds (E = Pb), element‐element multiple bonds (E = P, As) and biradical ground states (E = N) are observed. Our results hint at the feasibility of NDI‐E 2 species as viable synthetic targets, highlighting the versatility and potential applications of napy ‐based ligands in main‐group chemistry.
Publisher: Wiley
Date: 30-06-2017
Abstract: Dihalodiboranes(4) react with a N-heterocyclic silylene (NHSi) to generate NHSi adducts of 1-aryl-2-silyl-1,2-diboraindanes, as was confirmed by X-ray crystallography, featuring the functionalization of both B-X (X=halogen) bonds and a sp
Publisher: American Chemical Society (ACS)
Date: 31-03-2016
Publisher: Wiley
Date: 16-01-2019
Publisher: Wiley
Date: 09-2008
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CS35510A
Abstract: Borylene ligands (:BR) are isolobal to CO and other iconic organometallic ligands. As such, borylene ligands enjoy some parallels to these ligands, but in many ways, their chemistry is distinct. This tutorial review gives an introduction to the synthesis, properties and reactivity of the major classes of transition metal borylene complexes, including terminal and bridging ex les, pseudoborylenes, and metalloborylenes (borido complexes).
Publisher: American Chemical Society (ACS)
Date: 22-05-2015
DOI: 10.1021/JACS.5B03805
Abstract: Reduction of 2-(BMes2)pyrene (B1) and 2,7-bis(BMes2)pyrene (B2) gives rise to anions with extensive delocalization over the pyrenylene bridge and between the boron centers at the 2- and 2,7-positions, the typically unconjugated sites in the pyrene framework. One-electron reduction of B2 gives a radical anion with a centrosymmetric semiquinoidal structure, while two-electron reduction produces a quinoidal singlet dianion with biradicaloid character and a relatively large S0-T1 gap. These results have been confirmed by cyclic voltammetry, X-ray crystallography, DFT/CASSCF calculations, NMR, EPR, and UV-vis-NIR spectroscopy.
Publisher: Elsevier BV
Date: 04-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3CC46947F
Abstract: Ethynyldimesitylborane (1) is synthesised via salt elimination and its reactivity towards NHCs is studied. Depending on their size, NHCs attack either at the boron atom or at the β-alkynyl carbon atom. Steric control over the reaction was probed by reactions with N-heterocyclic carbenes yielding a carbene-borane adduct (2), a 1-boraindane (3), and the first structurally characterised borataallene (4).
Publisher: Wiley
Date: 27-07-2009
Publisher: American Chemical Society (ACS)
Date: 04-11-2014
DOI: 10.1021/OM500875G
Publisher: Wiley
Date: 11-10-2021
Abstract: A number of novel alkynyl‐functionalized diarylbis(dimethylamino)diboranes(4) are prepared by salt metathesis, and the appended alkynyl groups are subjected to hydroboration. Their reactions with monohydroboranes lead to discrete boryl‐appended diborane(4) species, while dihydroboranes induce their catenation to oligomeric species, the first known ex les of well‐characterized macromolecular species with B−B bonds. The oligomeric species were found to comprise up to ten repeat units and are soluble in common organic solvents. Some of the oligomeric species have good air stability and all were characterized by NMR and vibrational spectroscopy and size‐exclusion chromatography techniques.
Publisher: Wiley
Date: 23-04-2018
Abstract: A family of doubly isonitrile-stabilized terphenyl borylenes could be obtained by addition of three equivalents of isonitrile to the corresponding Cr and W terminal terphenyl-borylene complexes. The mechanism of isonitrile- and carbon-monoxide-induced borylene liberation was investigated computationally and found to be significantly exergonic in both cases. Furthermore, addition of a small N-heterocyclic carbene (NHC) to a terminal Cr borylene complex results in release of an NHC-stabilized borylene carbonyl species, whereas the analogous reaction with bulkier phosphines results in metal-centered substitution.
Publisher: American Chemical Society (ACS)
Date: 29-11-2016
DOI: 10.1021/JACS.6B10609
Abstract: The combination of Pt
Publisher: Wiley
Date: 25-04-2018
Abstract: Zwei isolierbare, neutrale, Basen‐stabilisierte Diborane(5) sind dazu in der Lage, ausschließlich durch ihre B‐B‐Bindung stark an mehrere Kupfer(I)‐Komplexe zu binden. Die resultierenden Komplexe repräsentieren die ersten bekannten Komplexe mit neutralen, ungeschützten σ B‐B ‐Diboranliganden. Die Einkristall‐Röntgenstrukturanalysen dieser Komplexe zeigen, dass die X‐Cu‐Einheit (X=Cl, OTf, C 6 F 5 ) gegenüber vom verbrückenden Wasserstoffatom des Diborans liegt und annähernd senkrecht zur B‐B‐Bindung steht. Dabei wechselwirkt diese nahezu gleichermaßen mit beiden Boratomen, woraus eine Verlängerung der B‐B‐Bindung resultiert. DFT‐Studien belegen, dass sowohl σ‐Donor‐ als auch π‐Akzeptor‐Effekte der B‐B‐Bindung für die Bildung dieser Produkte verantwortlich sind. Erstaunlicherweise zeigen sich diese Kupfer‐σ B‐B ‐Komplexe inert gegen thermisch oder photolytisch induzierten Ligandenaustausch mit Pyridin.
Publisher: Wiley
Date: 11-11-2013
Abstract: Mono- and dinuclear hydridoborylene complexes were prepared by intermetallic borylene transfer from Group VI borylene or metalloborylene reagents. The hydride and borylene ligands were found to interact with each other significantly, although the boron ligand retains much of its former borylene character. Zero-valent platinum fragments were successively added to the dinuclear hydridoborylene complexes, resulting in tri- and tetranuclear borido complexes, in which the B-H interaction has been lost, and the hydride ligands now bridge two metal centers. The complexes were studied spectroscopically, crystallographically, and by DFT methods, and the unusual bonding situation in the M-B-H triangles of hydridoborylene complexes were evaluated.
Publisher: Wiley
Date: 20-06-2008
Publisher: Wiley
Date: 22-12-2022
Abstract: Carbenstabilisierte Diborine der Form LBBL (L= N ‐heterocyclisches Carben (NHC) oder cyclisches Alkyl(amino)carben (CAAC)) induzieren bei Raumtemperatur eine schnelle, ertragreiche, intermolekulare ortho‐C‐H‐Borylierung an N ‐Heterocyclen. Ein einfaches Pyridyldiboren wird gebildet, wenn ein NHC‐stabilisiertes Diborin mit Pyridin kombiniert wird, während ein CAAC‐stabilisiertes Diborin zur Aktivierung von zwei Pyridinmolekülen führt, um ein tricyclisches Alkylidenboran zu bilden, das durch Erhitzen zu einem zwitterionischen, zweifach benzokondensierten 1,3,2,5‐Diazadiborinin mittels einer weiteren H‐Verschiebung umgelagert werden kann. Die Verwendung des verlängerten N ‐heteroaromatischen Chinolins führt unter milden Bedingungen über einen bisher unbekannten Bor‐Kohlenstoff‐Austauschprozess zu einem Borylmethylenboran.
Publisher: Wiley
Date: 26-06-2014
Abstract: The photoionization and dissociative photoionization of 1,4-di-tert-butyl-1,4-azaborinine by means of synchrotron radiation and threshold photoelectron photoion coincidence spectroscopy is reported. The ionization energy of the compound was determined to be 7.89 eV. Several low-lying electronically excited states in the cation were identified. The various pathways for dissociative photoionization were modeled by statistical theory, and appearance energies AE0K were obtained. The loss of isobutene in a retro-hydroboration reaction is the dominant pathway, which proceeds with a reverse barrier. Pyrolysis of the parent compound in a chemical reactor leads to the generation of several yet unobserved boron compounds. The ionization energies of the C4 H6 BN isomers 1,2- and 1,4-dihydro-1,4-azaborinine and the C3 H6 BN isomer 1,2-dihydro-1,3-azaborole were determined from threshold photoelectron spectra.
Publisher: Wiley
Date: 13-09-2016
Abstract: The first terminal manganese phosphinidene complex was quantitatively synthesized from a terminal alkylborylene complex. Its structure and bonding, as well as the reaction mechanism, were investigated through a combination of experimental and computational studies.
Publisher: Wiley
Date: 02-03-2009
Abstract: A reaction with many facets: The facile dehydrogenative synthesis of a borylene complex (left in scheme) from a dihydroborane (right), proceeds reversibly at room-temperature. The implications of this reaction for the fields of inorganic, main-group, and hydrogen-storage chemistry are covered in this Highlight.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CC03148C
Abstract: Convenient solution-phase syntheses of tetrahalodiboranes(4) and the dimethylsulfide adducts B 2 Cl 4 (SMe 2 ) 2 and B 2 Br 4 (SMe 2 ) 2 are presented.
Publisher: Wiley
Date: 09-04-2014
Abstract: Despite the synthesis of a boryl anion by Yamashita et al. in 2006, compounds that show boron-centered nucleophilicity are still rare and sought-after synthetic goals. A number of such boryl anions have since been prepared, two of which were reported to react with methyl iodide in apparent nucleophilic substitution reactions. One of these, a borolyl anion based on the borole framework, has now been found to display single-electron-transfer (SET) reactivity in its reaction with triorganotetrel halides, which was confirmed by the isolation of the first neutral borole-based radical. The radical was characterized by elemental analysis, single-crystal X-ray crystallography, and EPR spectroscopy, and has implications for the understanding of boron-based nucleophilic behavior and the emergent role of boron radicals in synthesis. This radical reactivity was also exploited in the synthesis of compounds with rare B-Sn and B-Pb bonds, the latter of which was the first isolated and structurally characterized compound with a "noncluster" B-Pb bond.
Publisher: Wiley
Date: 16-01-2019
Abstract: A number of recently discovered nucleophilic boron compounds, such as boryl anions and borylenes, are breaking the rules regarding boron and boron-containing compounds and their reputation as Lewis acids/electrophiles. In a similar fashion, the B-H bonding pair electrons in boranes also show nucleophilicity which is ascribed to the lower electronegativity of boron relative to that of hydrogen. However, this nucleophilicity of the B-H bond has received far less attention. Explorations of the nucleophilicity of the B-H bonding pair electrons have led to the formation of B-H-B bonded units and B-H⋅⋅⋅H-Y dihydrogen bonds, based on which new chemistry has been uncovered, including the elucidation of the mechanism of formation of aminodiborane (ADB), the diammoniate of diborane (DADB), and lithium or sodium salts of octahydrotriborates (B
Publisher: Wiley
Date: 08-06-2018
Abstract: A range of double carbene adducts of digallanes(4) are prepared from an existing double digallane adduct, and their halides are subsequently exchanged, establishing the feasibility of both base and halide-exchange reactions from digallane adducts. Furthermore, a range of digallium species are treated with transition-metal Lewis bases, leading alternatively to oxidative addition products, species with monocoordinate Ga
Publisher: Wiley
Date: 07-12-2017
Publisher: American Association for the Advancement of Science (AAAS)
Date: 23-02-2018
Abstract: Although diatomic nitrogen is famously inert, a variety of transition metals can bind to it through a process termed backbonding. As the nitrogen weakly shares its own electrons, some electrons from the metal reach back out to it. Nonmetals would not seem to have the capacity for this type of bonding, but now Légaré et al. show that conventionally electron-deficient boron can be coaxed into it (see the Perspective by Broere and Holland). The authors treated boron-based precursors with potassium under a nitrogen atmosphere to produce several compounds with sandwiched dinitrogen between two boron centers in reduced motifs reminiscent of metal complexes. Science , this issue p. 896 see also p. 871
Publisher: Wiley
Date: 13-08-2018
Abstract: Diaryldihalodiboranes(4) were reacted with bis(amidinato)- and bis(guanidinato)silylenes to generate the first neutral diborane-centered radicals. These formally non-aromatic 5π electron systems are stable in the solid state as well as in solution and were characterized by solid-state structure determination, high-resolution mass spectrometry, and EPR spectroscopy. The reactivity of one of these radicals with the oxidant 1,4-benzoquinone led to ring-opening and B-O bond formation.
Publisher: Wiley
Date: 05-2021
Abstract: Das NHC‐stabilisierte Diborin B 2 (SIDep) 2 (SIDep=1,3‐Bis(2,6‐diethylphenyl)imidazolin‐2‐yliden) unterzieht sich bei Raumtemperatur einer P‐P‐Bindungsaktivierung mit Tetraethyldiphosphan, wobei mittels 1,2‐Diphosphinierung über ein Diphosphoryldiboren in hohen Ausbeuten B 2 P 2 ‐Heterocyclen gebildet werden. In Abhängigkeit vom verwendeten Oxidationsmittel und Gegenion kann dieser Heterocyclus zu einem Radikalkation beziehungsweise Dikation oxidiert werden. Beginnend mit dem planaren, neutralen 1,3‐Bis(alkyliden)‐1,3‐diborata‐2,4‐diphosphoniocyclobutan führt jeder Oxidationsschritt zu einer verminderten B‐B‐Bindungslänge und dem Verlust der Planarität durch die Kationisierung. Röntgenstrukturanalysen in Kombination mit DFT‐ und CASSCF/NEVPT2‐Rechnungen offenbaren für die NHC‐stabilisierten dikationischen B 2 P 2 ‐Ringe geschlossenschalige, schmetterlingsartige Strukturen, wovon die diradikaloiden Isomere mit planarem Ring in energetischer Nähe liegen.
Publisher: Wiley
Date: 05-06-2017
Publisher: Wiley
Date: 11-10-2021
Abstract: A 1,8‐naphthyridine diphosphine (NDP) reacts with boron‐containing Lewis acids to generate complexes featuring a number of different naphthyridine bonding modes. When exposed to diborane B 2 Br 4 , NDP underwent self‐deprotonation to afford [NDP‐B 2 Br 3 ]Br, an unsymmetrical diborane comprised of four fused rings. The reaction of two equivalents of monoborane BBr 3 and NDP in a non‐polar solvent provided the simple phosphine‐borane adduct [NDP(BBr 3 ) 2 ], which then underwent intramolecular halide abstraction to furnish the salt [NDP‐BBr 2 ][BBr 4 ], featuring a different coordination mode from that of [NDP‐B 2 Br 3 ]Br. Direct deprotonation of NDP by KHMDS or PhCH 2 K generates mono‐ and dipotassium reagents, respectively. The monopotassium reagent reacts with one or half an equivalent of B 2 (NMe 2 ) 2 Cl 2 to afford NDP‐based diboranes with three or four amino substituents.
Publisher: American Chemical Society (ACS)
Date: 21-05-2013
DOI: 10.1021/JA403389W
Abstract: A comprehensive study has been carried out to investigate the metathesis reactivity of the terminal alkylborylene complex [(η(5)-C5H5)(OC)2Mn═B(tBu)] (1). Its reactions with 3,3',5,5'-tetrakis(trifluoromethyl)benzophenone, 4,4'-dimethylbenzophenone, 2-adamantanone, 4,4'-bis(diethylamino)benzophenone, and 1,2-diphenylcyclopropen-3-one afforded the metathesis products [(η(5)-C5H5)(OC)2Mn═CR2] (R = C6H3-3,5-(CF3)23a, C6H4-4-Me 3b, C6H4-4-NEt23d CR2 = adamantylidene 3c, cyclo-C3Ph23e). The cycloaddition intermediates were detected by NMR spectroscopy from reactions involving ketones with more electron-withdrawing substituents. The reaction of 1 with dicyclohexylcarbodiimide (DCC) only proceeds to form the cycloaddition product [(η(5)-C5H5)(OC)2Mn{κ(2)-C,B-C(═NCy)N(Cy)B(tBu)}] (4), which upon warming, rearranges to afford complex [(η(5)-C5H5)(OC)2Mn{CN(Cy)B(tBu)CN(Cy)}] (5). The reaction of 1 with triphenylphosphine sulfide SPPh3 also yields the metathesis product [(η(5)-C5H5)(OC)2Mn(PPh3)] via an intermediate which is likely to be a η(2)-thioboryl complex [(η(5)-C5H5)(OC)2Mn{(η(2)-SB(tBu)}] (6). Similar reactions have been studied using an iron borylene complex [(Me3P)(OC)3Fe═B(Dur)] (Dur = 2,3,5,6-tetramethylphenyl, 9). Extensive computational studies have been also carried out to gain mechanistic insights in these reactions, which provided reaction pathways that fit well with the experimental data.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7SC03193A
Abstract: Anionic organic sp 3 -, sp 2 - and sp-nucleophiles as well as neutral Lewis bases were shown to add to a coordinatively saturated cyclic (alkyl)(amino)carbene (cAAC) supported borane thanks to reversible transfer of a hydrogen atom from boron to the adjacent Lewis acidic cAAC carbene carbon atom.
Publisher: Wiley
Date: 06-04-2020
Abstract: Boron's unique position in the Periodic Table, that is, at the apex of the line separating metals and nonmetals, makes it highly versatile in chemical reactions and applications. Contemporary demand for renewable and clean energy as well as energy‐efficient products has seen boron playing key roles in energy‐related research, such as 1) activating and synthesizing energy‐rich small molecules, 2) storing chemical and electrical energy, and 3) converting electrical energy into light. These applications are fundamentally associated with boron's unique characteristics, such as its electron‐deficiency and the availability of an unoccupied p orbital, which allow the formation of a myriad of compounds with a wide range of chemical and physical properties. For ex le, boron's ability to achieve a full octet of electrons with four covalent bonds and a negative charge has led to the synthesis of a wide variety of borate anions of high chemical and electrochemical stability—in particular, weakly coordinating anions. This Review summarizes recent advances in the study of boron compounds for energy‐related processes and applications.
Publisher: Wiley
Date: 07-09-2011
Abstract: A stable trans-(alkyl)(boryl) platinum complex trans-[Pt(BCat')Me(PCy(3))(2)] (Cat'=Cat-4-tBu Cy=cyclohexyl=C(6)H(11)) was synthesised by salt metathesis reaction of trans-[Pt(BCat')Br(PCy(3))(2)] with LiMe and was fully characterised. Investigation of the reactivity of the title compound showed complete reductive elimination of Cat'BMe at 80 °C within four weeks. This process may be accelerated by the addition of a variety of alkynes, thereby leading to the formation of the corresponding η(2) -alkyne platinum complexes, of which [Pt(η(2)-MeCCMe)(PCy(3))(2)] was characterised by X-ray crystallography. Conversion of the trans-configured title compound to a cis derivative remained unsuccessful due to an instantaneous reductive elimination process during the reaction with chelating phosphines. Treatment of trans-[Pt(BCat')Me(PCy(3))(2)] with Cat(2)B(2) led to the formation of CatBMe and Cat'BMe. In the course of further investigations into this reaction, indications for two indistinguishable reaction mechanisms were found: 1) associative formation of a six-coordinate platinum centre prior to reductive elimination and 2) σ-bond metathesis of B-B and C-Pt bonds. Mechanism 1 provides a straightforward explanation for the formation of both methylboranes. Scrambling of diboranes(4) Cat(2)B(2) and Cat'(2)B(2) in the presence of [Pt(PCy(3))(2)], fully reductive elimination of CatBMe or Cat'BMe from trans-[Pt(BCat')Me(PCy(3))(2)] in the presence of sub-stoichiometric amounts of Cat(2)B(2), and evidence for the reversibility of the oxidative addition of Cat(2)B(2) to [Pt(PCy(3))(2)] all support mechanism 2, which consists of sequential equilibria reactions. Furthermore, the solid-state molecular structure of cis-[Pt(BCat)(2)(PCy(3))(2)] and cis-[Pt(BCat')(2)(PCy(3))(2)] were investigated. The remarkably short B-B separations in both bis(boryl) complexes suggest that the two boryl ligands in each case are more loosely bound to the Pt(II) centre than in related bis(boryl) species.
Publisher: American Chemical Society (ACS)
Date: 20-06-2014
DOI: 10.1021/OM5002414
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CC05325J
Abstract: A bis(germylene) based on a naphthyridinediamine (NDI) is reported. Calculations on the [NDI-Ge 2 ][Fe 2 (CO) 6 ] complex revealed the six-electron donor behavior of NDI-Ge 2 , the first of its kind for bidentate ligands based on group 14 elements.
Publisher: Wiley
Date: 25-04-2018
Abstract: Herein we report the discovery that two bottleable, neutral, base‐stabilized diborane(5) compounds are able to bind strongly to a number of copper(I) complexes exclusively through their B−B bond. The resulting complexes represent the first known complexes containing unsupported, neutral σ B−B diborane ligands. Single‐crystal X‐ray analyses of these complexes show that the X−Cu moiety (X=Cl, OTf, C 6 F 5 ) lies opposite the bridging hydrogen atom of the diborane and is near perpendicular to the B−B bond, interacting almost equally with both boron atoms and causing a B−B bond elongation. DFT studies show that σ donation from and π backdonation to the pseudo‐π‐like B−B bond account for their formation. Astoundingly, these copper σ B−B complexes are inert to ligand exchange with pyridine under either heating or photoirradiation.
Publisher: Wiley
Date: 25-07-2013
Abstract: Partial metal-boron bond cleavage and coupling of a borylene with two CO ligands was observed upon reduction of a new bulky arylborylene complex. Both the borylene precursor and dianionic product were structurally and spectroscopically characterized. In contrast, reduction of an aminoborylene complex led to complete loss of the borylene ligand and classical Hieber reduction. A rationale for these differences based on DFT methods is presented.
Publisher: American Chemical Society (ACS)
Date: 08-2017
DOI: 10.1021/JACS.7B06644
Abstract: Despite the prevalence of stable π-complexes of most d
Publisher: Wiley
Date: 24-03-2011
Publisher: Wiley
Date: 20-01-2012
Abstract: Upon treating transition-metal-dihaloboryl complexes of the form [L(n)MBX(2)] with K[(η(5)-C(5)H(5))MnH(CO)(2)], salt elimination occurs along with a migration of the Mn-bound hydride ligand onto the boron atom, thereby forming dinuclear σ-(halo)boranyl complexes of the form [L(n)M(μ-BHX)Mn(CO)(2)(η(5)-C(5)H(5))]. Most of these complexes react further at room temperature to lose HX and provide metalloborylene complexes [L(n)M-B = Mn(CO)(2)(η(5)-C(5)H(5))] however, when ML(n) = Re(CO)(5) the σ-(halo)boranyl complex decomposes into unidentifiable products. We found through DFT calculations that two electronically and structurally distinct forms of the intermediate σ-(halo)boranyl complexes exist, one of which easily loses HX and one that does not.
Publisher: SAGE Publications
Date: 14-09-2021
DOI: 10.1177/19476035211044822
Abstract: Mesenchymal stem/stromal cells (MSCs) are a well-established cell source for cartilage engineering, but challenges remain as differentiation often results in chondrocyte hypertrophy. Chondrogenic potential also varies with MSC source and donor age. We assessed the chondrogenic potential of first-trimester and term placental MSCs and compared their response to commonly used bone marrow MSCs (BM-MSCs). MSCs were isolated from first-trimester and term placentae. BM-MSCs were commercially obtained. Chondrogenesis was induced by micromass culture in commercial chondrogenic media for 7, 14, or 21 days. Pellets were assessed for glycosaminoglycan (GAG) content, and types I, II, and X collagen. Gene expression was profiled using Qiagen RT2 human MSC arrays. At day 0, first-trimester and term MSCs expression levels of many chondrogenic genes to BM-MSC after 21 days of culture. Only first trimester MSCs showed significant changes in chondrogenic gene expression during induction compared to day 0 undifferentiated MSCs (greater BMP4, KAT2B, and reduced GDF6 expression). Additionally, first-trimester MSCs showed significantly greater expression of ABCB1 (at days 14 and 21) and BMP4 (at days 7, 14, 21) compared with term MSCs. Both first-trimester and term pellets showed increased GAG content over time and term MSCs had significantly GAG greater compared with BM-MSCs at days 7 and 14. Type II collagen was present in all pellets but unlike BM-MSCs, type I collagen was not observed in first-trimester or term MSC pellets. These data highlight differences in BM-MSC and placental MSC chondrogenesis and demonstrate that placental MSCs may be an alternative cell source.
Publisher: Wiley
Date: 15-07-2018
Publisher: Wiley
Date: 21-12-2020
Publisher: Springer Science and Business Media LLC
Date: 13-05-2023
DOI: 10.1038/S41467-023-36251-3
Abstract: The Fischer carbene synthesis, involving the conversion of a transition metal (TM)-bound CO ligand to a carbene ligand of the form [=C(OR’)R] (R, R’ = organyl groups), is one of the seminal reactions in the history of organometallic chemistry. Carbonyl complexes of p -block elements, of the form [E(CO) n ] (E = main-group fragment), are much less abundant than their TM cousins this scarcity and the general instability of low-valent p-block species means that replicating the historical reactions of TM carbonyls is often very difficult. Here we present a step-for-step replica of the Fischer carbene synthesis at a borylene carbonyl involving nucleophilic attack at the carbonyl carbon followed by electrophilic quenching at the resultant acylate oxygen atom. These reactions provide borylene acylates and alkoxy-/silyloxy-substituted alkylideneboranes, main-group analogues of the archetypal transition metal acylate and Fischer carbene families, respectively. When either the incoming electrophile or the boron center has a modest steric profile, the electrophile instead attacks at the boron atom, leading to carbene-stabilized acylboranes – boron analogues of the well-known transition metal acyl complexes. These results constitute faithful main-group replicas of a number of historical organometallic processes and pave the way to further advances in the field of main-group metallomimetics.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CC45455J
Abstract: The first ex les of σ-coordinated metal-haloboryl complexes have been synthesised. The haloboryl moiety may be functionalized by nucleophilic substitution reactions, by which more electron-withdrawing substituents may be installed at the boron center.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1SC05988B
Abstract: The ground-state multiplicity of dicoordinate borylenes, which dictates their reactivity, is tuned by the nature of the stabilising carbene ligand.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CC01493C
Abstract: Two surprising new outcomes of the reaction of Lewis bases with dihalodiboranes(4) are presented.
Publisher: Springer Science and Business Media LLC
Date: 06-06-2016
DOI: 10.1038/NCHEM.2542
Abstract: The metals of the s block of the periodic table are well known to be exceptional electron donors, and the vast majority of their molecular complexes therefore contain these metals in their fully oxidized form. Low-valent main-group compounds have recently become desirable synthetic targets owing to their interesting reactivities, sometimes on a par with those of transition-metal complexes. In this work, we used stabilizing cyclic (alkyl)(amino)carbene ligands to isolate and characterize the first neutral compounds that contain a zero-valent s-block metal, beryllium. These brightly coloured complexes display very short beryllium-carbon bond lengths and linear beryllium coordination geometries, indicative of strong multiple Be-C bonding. Structural, spectroscopic and theoretical results show that the complexes adopt a closed-shell singlet configuration with a Be(0) metal centre. The surprising stability of the molecule can be ascribed to an unusually strong three-centre two-electron π bond across the C-Be-C unit.
Publisher: Royal Society of Chemistry (RSC)
Date: 15-07-2014
DOI: 10.1039/C4SC01539H
Publisher: Wiley
Date: 24-11-2016
Abstract: An electron-rich monovalent boron compound is used as a Lewis base to prepare adducts with Group 13 Lewis acids using both its boron and nitrogen sites. The hard Lewis acid AlCl3 binds through a nitrogen atom of the Lewis base, while softer Lewis acids GaX3 (Cl, Br, I) bind at the boron atom. The latter are the first noncluster Lewis adducts between a boron-centered Lewis base and a main-group Lewis acid.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9SC02544H
Abstract: A set of diboryldiborenes are prepared by the mild, catalyst-free, room-temperature diboration of the B–B triple bonds of doubly base-stabilized diborynes.
Publisher: American Chemical Society (ACS)
Date: 22-05-2012
DOI: 10.1021/CR3000048
Publisher: Wiley
Date: 12-03-2014
Abstract: New metal-only Lewis pairs (MOLPs: Ru→Cr and Os→Cr) are prepared by the insertion of a zerovalent ruthenium or osmium complex into chromium-boron double bonds of borylene complexes. The reaction creates new borylene complexes (the first ever for osmium), and is crystallization-controlled re-dissolving the complexes results in regeneration of the starting materials. A mechanism is proposed based on DFT calculations, along with a computational study of the unusual MOLPs.
Publisher: Wiley
Date: 07-12-2017
Abstract: The reaction of tetraiododiborane (B
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7SC04789D
Abstract: This side-by-side reactivity study of a borylene and a diborene with the same empirical formula demonstrates their non-interconvertibility.
Publisher: Wiley
Date: 09-05-2016
Abstract: The reaction of the salts K[Ru(CO)3 (PMe3 )(SiR3 )] (R=Me, Et) with Br2 BDur or Cl2 BDur (Dur=2,3,5,6-Me4 C6 H) leads to both boryl and borylene complexes of alent ruthenium, the former through simple salt elimination and the latter through subsequent CO loss and 1,2-halide shift. The balance of products can be altered by varying the reaction conditions boryl complexes can be favored by the addition of CO, and borylene complexes by removal of CO under vacuum. All of these products are in competition with the corresponding (aryl)(halo)(trialkylsilyl)borane, a reductive elimination product. The Ru(II) borylene products and the mechanisms that form them are distinctly different from the analogous reactions with iron, which lead to low-valent borylene complexes, highlighting fundamental differences in oxidation state preferences between iron and ruthenium.
Publisher: Wiley
Date: 22-03-2019
Abstract: The lability of B=B, B-P, and B-halide bonds is combined in the syntheses of the first diiododiborenes. In a series of reactivity tests, these diiododiborenes undergo cleavage of all six of their central bonds in different ways, leading to products of B=B hydrogenation and dihalogenation as well as halide exchange.
Publisher: International Union of Crystallography (IUCr)
Date: 17-10-2009
Publisher: Walter de Gruyter GmbH
Date: 06-2013
Abstract: The first base-stabilized iodoborylene platinum complex was prepared through the addition of 4-picoline (4-Pic) to a suspension of an iodo-bridged binuclear iodoboryl complex. An X-ray structure determination of the title compound has characterized the molecular structure as cis-[Pt{BI(4- Pic)}I 2 (PCy 3 )]. The bond lengths lie in the expected range for neutral, base-stabilized borylene complexes. The strong trans influence of the borylene moiety is reflected in the longer Pt-1 distance for the iodo ligand opposite the borylene, compared to that opposite the phosphine ligand
Publisher: Wiley
Date: 17-09-2019
Abstract: The steric and electronic properties of aryl substituents in monoaryl borohydrides (Li[ArBH 3 ]) and dihydroboranes were systematically varied and their reactions with [Ru(PCy 3 ) 2 HCl(H 2 )] (Cy: cyclohexyl) were studied, resulting in bis(σ)‐borane or terminal borylene complexes of ruthenium. These variations allowed for the investigation of the factors involved in the activation of dihydroboranes in the synthesis of terminal borylene complexes. The complexes were studied by multinuclear NMR spectroscopy, mass spectrometry, X‐ray diffraction analysis, and density functional theory (DFT) calculations. The experimental and computational results suggest that the ortho ‐substitution of the aryl groups is necessary for the formation of terminal borylene complexes.
Publisher: Wiley
Date: 22-01-2021
Publisher: Wiley
Date: 22-01-2021
Publisher: Wiley
Date: 27-12-2020
Publisher: Wiley
Date: 30-01-2013
Abstract: The construction of boron-boron bonds, despite the intense synthetic interest in diboranes and the high B-B bond enthalpy, is still difficult, uncontrollable, and unpredictable. Methods for the construction of B-B multiple bonds are rarer still. These problems have witnessed some progress in recent years this Minireview attempts to provide a background to the history of B-B bond synthesis and summarize the recent results in the area.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2SC01436J
Abstract: Attempts to form a base-stabilised arylalumylene by reducing an NHC-coordinated diiodoterphenylalane led to a masked dialumene. Reactivity studies showed it decouples to initially aimed arylalumylene, which easily deconstructs less reactive arenes.
Publisher: American Chemical Society (ACS)
Date: 11-03-2015
DOI: 10.1021/ACS.INORGCHEM.5B00091
Abstract: Terminal borylene complexes of group 6-10 metals have been prepared through a number of synthetic strategies, displaying a wide structural ersity with numerous coordination modes of the borylene ligand [:BR]. Earlier, amino-substituted borylenes were found to serve as borylene ligand transfer reagents to a range of organic and organometallic substrates. In contrast, aryl- and alkyl-substituted borylenes display metathesis behavior when combined with ketones. Recent studies on these complexes revealed new reactivity patterns involving borylene-borylene and carbonyl-borylene ligand coupling. Herein a brief account on the recent progress of these borylene ligand coupling reactions made in our laboratories is provided. These reactions offer unprecedented alternative methods for electron-precise B-B and B-C bond formation.
Publisher: Wiley
Date: 17-01-2012
Publisher: American Chemical Society (ACS)
Date: 10-02-2021
Publisher: Springer Science and Business Media LLC
Date: 09-12-2013
DOI: 10.1038/NCHEM.1520
Abstract: Transition-metal catalysis is founded on the principle that electron donation from a metal to a ligand is accepted by an antibonding orbital of the ligand, thereby weakening one of the bonds in the ligand. Without this, the initial step of bond activation in many catalytic processes would simply not occur. This concept is enshrined in the well-accepted Dewar-Chatt-Duncanson model of transition-metal bonding. We present herein experimental and computational evidence for the first true violation of the Dewar-Chatt-Duncanson bonding model, found in a π-diborene complex in which an electron-rich group 10 metal donates electrons into an empty bonding π orbital on the ligand, and thereby strengthens the bond. The complex is also the first transition-metal complex to contain a bound diborene, a species not isolated before, either in its free form or bound to a metal.
Publisher: Wiley
Date: 30-04-2015
Publisher: Wiley
Date: 09-04-2010
Publisher: Wiley
Date: 11-01-2019
Abstract: A new structural class of boron-based diradicals is prepared by Lewis base addition to and reduction of singly cyclic (alkyl)(amino)carbene (CAAC) stabilised diborylalkenes. The diradicals feature a perpendicular olefinic bridge preventing delocalization between the B(CAAC) π systems, making the coupling between the spin centres very weak. DFT calculations indicate that the compounds are ground-state (open-shell) singlets, with triplet states negligibly higher in energy, thus making the triplet states easily populated thermally.
Publisher: Wiley
Date: 04-08-2015
Abstract: An improved synthetic route to homoleptic complex [Pt(CAAC(Me))2] (CAAC = cyclic (alkyl)(amino)carbenes) and convenient routes to new heteroleptic complexes of the form [Pt(CAAC(Me))(PR3)] are presented. Although the homoleptic complex was found to be inert to many reagents, oxidative addition and metal-only Lewis pair (MOLP) formation was observed from one of the heteroleptic complexes. The spectroscopic, structural, and electrochemical properties of the zero-valent complexes were explored in concert with density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. The homoleptic [Pt(CAAC)2] and heteroleptic [Pt(CAAC)(PR3)] complexes were found to be similar in their spectroscopic and structural properties, but their electrochemical behavior and reactivity differ greatly. The unusually strong color of the CAAC-containing Pt(0) complexes was investigated by TD-DFT calculations and attributed to excitations into the LUMOs of the complexes, which are predominantly composed of bonding π interactions between Pt and the CAAC carbon atoms.
Publisher: Wiley
Date: 06-02-2015
Abstract: A number of unprecedented photophysical phenomena were observed in the study of luminescent π-diborene complexes of Cu and Ag. These observations included unusually high fluorescence quantum yields (up to 100%) in solution for complexes of these metals. This result indicates that very little or no intersystem crossing between S1 and T(n) occurs in the complexes, despite the strong spin-orbit coupling of the metal atoms. The replacement of carbon with boron thus yields luminescent isolobal analogues of otherwise non-emissive olefin complexes of Cu and Ag.
Publisher: Wiley
Date: 31-01-2013
Publisher: Wiley
Date: 18-05-2015
Publisher: Wiley
Date: 18-11-2009
Publisher: American Chemical Society (ACS)
Date: 18-02-2022
DOI: 10.1021/JACS.2C00479
Publisher: Wiley
Date: 25-10-2011
Publisher: Wiley
Date: 20-11-2012
Abstract: Cyclic complex 2 with bridging carbonyl ligands was synthesized from a facile and reversible intermolecular carbonyl-borylene ligand coupling reaction at room temperature. Complex 2 exhibits an unprecedented coordination mode for boron-metal complexes, which is also reflected in its remarkable (11)B NMR chemical shift of -57.2 ppm. Findings from spectroscopic, X-ray, and computational studies are presented, along with a proposed mechanism.
Publisher: Wiley
Date: 15-06-2012
Publisher: Wiley
Date: 15-05-2013
Abstract: We herein report detailed investigations into the interaction of Lewis acidic fluoroboranes, for ex le BF2Pf (Pf=perfluorophenyl) and BF2Ar(F) (Ar(F)=3,5-bis(trifluoromethyl)phenyl), with Lewis basic platinum complexes such as [Pt(PEt3)3] and [Pt(PCy3)2] (Cy=cyclohexyl). Two presumed Lewis adducts could be identified in solution and corresponding secondary products of these Lewis adducts were characterized in the solid state. Furthermore, the concept of frustrated Lewis pairs (FLP) was applied to the activation of ethene in the system [Pt(BPf3)(CH2CH2)(dcpp)] (dcpp=1,3-bis(dicyclohexylphosphino)propane Pf=perfluorophenyl). Finally, DFT calculations were performed to determine the interaction between the platinum-centered Lewis bases and the boron-centered Lewis acids. Additionally, several possible mechanisms for the oxidative addition of the boranes BF3, BCl3, and BF2Ar(F) to the model complex [Pt(PMe3)2] are presented.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4SC02948H
Abstract: Halide groups are sequentially removed from platinum complexes containing tin and lead dihalide ligands, creating novel mono- and dicationic complexes.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5SC00211G
Abstract: The M-(η 2 -BMn) complex [(η 5 -C 5 H 5 )(OC) 2 Mn{μ-B(Cl)( t Bu)Au(PPh 3 )}] ( 2 ) can be functionalized via halide substitution reactions to afford isostructural complexes [(η 5 -C 5 H 5 )(OC) 2 Mn{μ-B(R)( t Bu)Au(PPh 3 )}] (R = Ph, CCPh and NCS).
Publisher: Wiley
Date: 15-03-2022
Abstract: Computational investigations were carried out to probe the potential of several dicoordinate, singly base‐stabilized borylenes of the form [L→BR] (L=neutral Lewis base) in dinitrogen binding. The calculated reaction free energies and activation barriers associated with the formation of mono‐ and diborylene‐N 2 adducts suggest the presence of thermally surmountable kinetic barriers towards their possible isolation. Our results show that the exergonicity of dinitrogen activation and fixation is linearly dependent on the natural charge at the boron center, which can be tuned to design novel boron‐based compounds with potential applications to small‐molecule activation. EDA‐NOCV analysis reveals strong binding of dinitrogen to these base‐stabilized borylenes.
Publisher: Wiley
Date: 19-08-2013
Abstract: The synthesis of base-stabilized boryl and borylene complexes is reported. An N-heterocyclic carbene (NHC)-stabilized iron-dihydroboryl complex was prepared by two different routes including methane liberation and salt elimination. A range of base-stabilized iron-dichloroboryl complexes was prepared by addition of Lewis bases to boryl complexes. Base-stabilized, cationic monochloroborylene complexes were synthesized from these boryl complexes by halide abstraction by using weakly coordinating anions.
Publisher: Wiley
Date: 05-06-2017
Abstract: The diborene 1 was synthesized by reduction of a mixture of 1,2-di-9-anthryl-1,2-dibromodiborane(4) (6) and trimethylphosphine with potassium graphite. The X-ray structure of 1 shows the two anthryl rings to be parallel and their π(C
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2SC02783F
Abstract: A bulky ferrocenyl-based NHC-stabilised aluminium( iii ) dihalide was reduced in different solvents, leading to vastly different outcomes, including formation of a rare ex le of a dialane and a novel dialuminyl analogue of the Birch reduction.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CC02316E
Abstract: The synthesis, structures and immense synthetic potential of sp 2 –sp 3 diboranes are reviewed and critically discussed.
Publisher: Wiley
Date: 11-11-2015
Abstract: A number of zerovalent ruthenium tri- and tetracarbonyl complexes of the form [Ru(CO)5-n Ln] (n=1, 2) with neutral phosphine or N-heterocyclic carbene donor ligands have been treated with the Lewis acids GaCl3 and Ag(+) to form a range of metal-only Lewis pairs (MOLPs). The spectroscopic and structural parameters of the adducts are compared to each other and to related iron carbonyl based MOLPs. The Lewis basicity of the original Ru(0) complexes is gauged by transfer experiments, as well as through the degree of pyramidization of the bound GaCl3 units and the Ru-M bond lengths. The work shows the benefits of the MOLP concept as one of the few direct experimental gauges of metal basicity, and one that can allow comparisons between metal complexes with different metal centers and ligand sets.
Publisher: American Chemical Society (ACS)
Date: 04-11-2011
DOI: 10.1021/JA208372K
Abstract: A novel NHC adduct of a dihalodiborane(4), 1, is reduced by KC(8) with formation of the five-membered boracycle 2. The reaction most likely proceeds via C-H insertion of an intermediate NHC-stabilized free bora-borylene species.
Publisher: American Chemical Society (ACS)
Date: 03-06-2013
DOI: 10.1021/JA403037K
Abstract: Apart from a few compounds under heavy use in organic chemistry, diboranes are relatively exotic and poorly understood. Recently, interest in these molecules has intensified with the advent of so-called "sp(2)-sp(3)" diboranes which exhibit useful reactivity toward organic substrates. In our hands, addition of Lewis bases to dihalodiorganyl diboranes(4) has previously shown some very surprising reactivity, including a substituent exchange between the boron atoms, and diboranes in which halide atoms bridge the B-B bond. Herein we have expanded the range of diborane(4) and Lewis base reaction partners, in the process uncovering three new reactivity patterns as well as some cases where mixtures are obtained. Trends are established for the preferential formation of certain products which rationalize the results based on electronic and steric effects. The substituent exchange, clearly based on an inorganic version of the well-known Wagner-Meerwein rearrangement, was also found to be an equilibrium reaction with the halide-bridged Lewis adducts on the other side.
Publisher: Wiley
Date: 30-01-2020
Publisher: Wiley
Date: 09-12-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CC35777A
Abstract: Mono- and diplatinum plumbylene complexes are prepared in which the bonding comprises synergic σ donation between the Pt and Pb atoms. The bonding distinguishes the complexes from both the classical Fischer carbene bonding model and M→Pb dative-only bonding. The Pt-Pb bond of the monoplatinum complex is stable, while the diplatinum complex reversibly loses one Pt fragment.
Publisher: American Chemical Society (ACS)
Date: 06-01-2014
DOI: 10.1021/OM401176H
Publisher: Wiley
Date: 06-05-2014
Abstract: The first ex le of a complex containing an η(3)-coordinated borirene ligand bound to a single metal atom was prepared by photolytic transfer of an arylborylene ligand to diphenylacetylene and loss of three CO ligands from the precursor. The η(3)-borirene complex possesses a chromium(0) atom which is also bound to one phenyl group in an η(6) fashion. The complex was isolated in 15% yield along with the corresponding metal-free borirene, which was isolated in 62% yield. The bonding between the chromium center and the borirene ring was studied computationally by DFT methods.
Publisher: American Chemical Society (ACS)
Date: 27-03-2017
DOI: 10.1021/JACS.7B00766
Abstract: Herein are reported the first π-complexes of compounds with boron-boron triple bonds with transition metals, in this case Cu
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4CC09036E
Abstract: The first monocyclic carbene-stabilised boriranes are prepared, and are found to be remarkably inert under forcing conditions despite their high ring strain.
Publisher: American Chemical Society (ACS)
Date: 05-09-2018
DOI: 10.1021/JACS.8B07644
Abstract: Cyclic (alkyl)(amino)carbenes (CAACs) and N-heterocyclic carbenes (NHCs) are widely used as stabilizing ligands in transition metal and main group element chemistry. Variations in their stabilizing properties have been cursorily explained in the literature by the greater π-donating and σ-accepting properties of CAACs relative to NHCs and their differing steric demands however, a more precise understanding, in particular a disentanglement of steric and electronic effects, is lacking. The recently reported compounds (E)(L)BB(L)(E) (L = NHC (I)/CAAC (II) and E = SPh) present a unique opportunity to investigate the differences between NHC and CAAC donors, as both forms are stable but differ considerably in their geometrical and electronic properties. The NHC systems possess a singlet ground state with a planar central SBBS unit, while their CAAC counterparts show a triplet ground state with a twisted SBBS unit. Steric effects were found to be important in this case however, it remained unclear how the different forms of twisting in I and II depend on the interplay of steric and electronic effects. In the present work we disentangle both effects. Our investigations explain all of these effects by MO considerations and show that for this kind of system the size of the singlet-triplet gaps are the key determinants of the differences. The different sizes of the S-T gaps result from variations in the antibonding effects within the highest occupied (HOMOs) and lowest unoccupied molecular orbitals (LUMOs). Our explanation seems to contradict the general scientific consensus about variations in the HOMO and LUMO of these two classes of cyclic carbenes however, comparisons to the Kekulé biradicaloids recently presented by Bertrand and co-workers indicate the generality of our approach.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CC13444B
Abstract: Intermetallic borylene transfer has been applied to synthesise new borido complexes. Starting from [{(η(5)-C(5)Me(5))Fe(CO)(2))}(μ-B){Cr(CO)(5)}] (1) the borylene moiety has been transferred successfully to different transition metal fragments. In the manner described, two new compounds have been fully characterised in solution and by X-ray crystallography.
Publisher: Wiley
Date: 05-2021
Abstract: The NHC‐stabilised diboryne (B 2 (SIDep) 2 SIDep=1,3‐bis(2,6‐diethylphenyl)imidazolin‐2‐ylidene) undergoes a high‐yielding P−P bond activation with tetraethyldiphosphine at room temperature to form a B 2 P 2 heterocycle via a diphosphoryldiborene by 1,2‐diphosphination. The heterocycle can be oxidised to a radical cation and a dication, respectively, depending on the oxidant used and its counterion. Starting from the planar, neutral 1,3‐bis(alkylidene)‐1,3‐diborata‐2,4‐diphosphoniocyclobutane, each oxidation step leads to decreased B−B distances and loss of planarity by cationisation. X‐ray analyses in conjunction with DFT and CASSCF/NEVPT2 calculations reveal closed‐shell singlet, butterfly‐shaped structures for the NHC‐stabilised dicationic B 2 P 2 rings, with their diradicaloid, planar‐ring isomers lying close in energy.
Publisher: Wiley
Date: 26-05-2021
Abstract: Cyclic alkyl(amino)carbene‐stabilized (cyano)hydroboryl anions were synthesized by deprotonation of (cyano)dihydroborane precursors. While they display boron‐centered nucleophilic reactivity towards organohalides, generating fully unsymmetrically substituted cyano(hydro)organoboranes, they show cyano‐nitrogen‐centered nucleophilic reactivity towards haloboranes, resulting in the formation of hitherto unknown linear 2‐aza‐1,4‐diborabutatrienes.
Publisher: Wiley
Date: 06-2023
Abstract: Low‐valent main group chemistry involves a balancing act between steric and electronic stabilization of the electron‐rich low oxidation state main group centers and their desired reactivity. Herein we show that the combination of sterically shielding mesityl and rotationally flexible 2‐thienyl groups, the latter having the potential to be either electronically stabilizing or activating, at a diborane(4) provides a platform for both radical anion stabilization and unusual bond activation and rearrangement reactions. The addition of a Lewis base to a 1,2‐dimesityl‐1,2‐dithienyldiborane(4) ( 1 ) results in direct and unprecedented C−H borylation of one thienyl substituent with cleavage of the B−B bond. The facile one‐electron reduction of 1 yields a stable diboron radical anion through delocalization of its unpaired electron over the entire planar 1,2‐dithienyldiboron framework, as evidenced by EPR spectroscopy and DFT calculations. The two‐electron reduction of 1 with magnesium anthracene under more forcing conditions results in B−B bond cleavage and replacement of one thienyl sulfur atom by a mesitylboron moiety, leading to the formation of a magnesium complex of an η 5 ‐diborafulvene dianion. Salt metathesis of the latter with [(η 6 ‐ p ‐cymene)RuCl 2 ] affords a mixed ruthenium sandwich complex of an η 5 ‐borylborole dianion. Calculations highlight both the structural and electronic changes in the boron‐substituted heterocyclic C 4 B dianion upon switching coordination from magnesium (diborafulvene dianion) to ruthenium (borylborole dianion).
Publisher: Wiley
Date: 06-2017
Publisher: Springer Science and Business Media LLC
Date: 22-03-2018
DOI: 10.1038/S41467-018-02998-3
Abstract: Molecules containing multiple bonds between atoms—most often in the form of olefins—are ubiquitous in nature, commerce, and science, and as such have a huge impact on everyday life. Given their prominence, over the last few decades, frequent attempts have been made to perturb the structure and reactivity of multiply-bound species through bending and twisting. However, only modest success has been achieved in the quest to completely twist double bonds in order to homolytically cleave the associated π bond. Here, we present the isolation of double-bond-containing species based on boron, as well as their fully twisted diradical congeners, by the incorporation of attached groups with different electronic properties. The compounds comprise a structurally authenticated set of diamagnetic multiply-bound and diradical singly-bound congeners of the same class of compound.
Publisher: International Union of Crystallography (IUCr)
Date: 13-02-2010
Publisher: Wiley
Date: 09-05-2016
Abstract: Heating the metalloborylene complex [{(η(5) -C5 Me5 )Fe(CO)2 }(μ-B){Cr(CO)5 }] with alkynes and diynes leads to the formation of B-metallated borirenes and a bis(B-metallated borirene) through formal transfer of the metalloborylene moiety [(η(5) -C5 Me5 )(OC)2 Fe(B:)]. By using this protocol, a range of B-metallated borirenes with electron-donating and electron-withdrawing substituents are prepared, and these are studied spectroscopically, structurally, and computationally. The yellow-orange color of the complexes is additionally explained through time-dependent density functional theory calculations.
Publisher: American Chemical Society (ACS)
Date: 20-11-2008
DOI: 10.1021/OM800883M
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CC03825F
Abstract: While lithium alkyls and lithium amides do not metallate the scandium compound [(η 5 -C 5 H 5 )Sc(η 8 -C 8 H 8 )], a synergistic lithium–aluminium base-trap partnership cannot resist taking a bite with one C–H bond selectively cleaved from both Cp and COT rings.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CC07681A
Abstract: The terminal borylene ligand is activated by Lewis bases to couple with terminal carbonyl ligands reversibly, initially forming a kinetic coupling product, which isomerises via a borylene migratory insertion to a cyclopentadienyl ligand C–H bond.
Publisher: Springer Science and Business Media LLC
Date: 14-09-2020
Publisher: Springer International Publishing
Date: 2015
Publisher: American Chemical Society (ACS)
Date: 14-07-2014
DOI: 10.1021/OM500596X
Publisher: American Chemical Society (ACS)
Date: 17-03-2010
DOI: 10.1021/CR900333N
Publisher: Wiley
Date: 16-04-2020
Publisher: Wiley
Date: 09-12-2019
Publisher: Wiley
Date: 19-02-2014
Abstract: Synthetic access to electron-precise boron chains is h ered by the preferential formation of nonclassical structures. The few existing strategies for this involve either strongly reducing reagents or transition-metal catalysts, both with distinct disadvantages. The synthesis of new furyl- and thienyl-substituted diborenes is presented, along with their direct hydroboration with catecholborane (CatBH) to form a new electron-precise B-B bond and a B3 chain. The reaction is diastereoselective and proceeds under mild conditions without the use of strong reducing agents or transition-metal catalysts commonly used in B-B coupling reactions.
Publisher: Wiley
Date: 15-07-2018
Abstract: B(sp
Publisher: Wiley
Date: 30-10-2014
Abstract: We present the isolation of the first mononuclear dihalogermylene, and mono- and dinuclear stannylene complexes of transition metals. These exhibit exceptionally pyramidalized Group 14 centers. Additionally, removal of the halide substituents from the Ge/Sn atom was successfully performed in two ways, halide abstraction and reduction, leading to a variety of unusual structural motifs.
Publisher: Wiley
Date: 30-01-2020
Publisher: American Chemical Society (ACS)
Date: 02-02-2023
DOI: 10.1021/ACS.INORGCHEM.5B00192
Abstract: The first ex les of heteroarylboryl complexes were prepared and have been found to be unreactive toward a range of strong reductants, strong Lewis bases, and halide-abstraction reagents. The inertness of the complexes is attributed to strong π-conjugation between the π-basic heteroaryl groups and the π-acidic boron atom. This hypothesis is supported by comparison of the structural and spectroscopic properties of the heteroarylboryl complexes with analogous previously reported homoarylboryl complexes, with the former showing greater coplanarity of the aryl ring with the boron atom and much less facile reactivity.
Publisher: Wiley
Date: 15-03-2016
Abstract: The complete scission of the carbon-oxygen bond of carbon monoxide, while frequently observed on bulk metals and with bimetallic and cluster transition metal complexes, is unknown with monometallic systems. Reaction of a zerovalent iron bis(borylene) complex with a cyclic (alkyl)(amino)carbene revealed a highly selective intramolecular cleavage of the C-O bond of a carbonyl ligand at room temperature, leading to the formation of a highly unusual iron complex containing a base-stabilized (bora)alkylideneborane ligand. DFT investigation of the reaction mechanism suggested that the two Lewis acidic borylene boron atoms cooperate to cleave the C-O multiple bond.
Publisher: Royal Society of Chemistry (RSC)
Date: 30-10-2014
DOI: 10.1039/C4CC08508F
Abstract: Stirring Lewis-basic transition metal complexes with the salts M[BAr(Cl)4] (M = Ag, Tl Ar(Cl) = 3,5-C6H3Cl2) resulted in the formation of diplatinum complexes [{(Cy3P)2Pt}2(μ-Ag)][BAr(Cl)4] (3) and [{(Cy3P)2Pt}2(μ-Tl)][BAr(Cl)4] (4) and the diiron compound [{(OC)3(Me3P)2Fe}2(μ-Ag)] (5) featuring bridging, unsupported metal cations. Their properties were investigated by multinuclear NMR spectroscopy, as well as X-ray diffraction and infrared measurements.
Publisher: Wiley
Date: 27-11-2015
Abstract: Ambient-temperature photolysis of the aminoborylene complex [(OC)5 Cr=B=N(SiMe3 )2 ] in the presence of a series of trans-bis(alkynyl)platinum(II) precursors of the type trans-[Pt(CCAr)2 (PEt3 )2 ] (Ar=Ph, p-C6 H4 OMe, and p-C6 H4 CF3 ) successfully leads to twofold transfer of the borylene moiety [:B=N(SiMe3 )2 ] onto the alkyne functionalities. The alkynyl precursors and resultant bis(borirene)platinum(II) complexes formed are of the type trans-[Pt(B{=N(SiMe3 )2 }C=CAr)2 (PEt3 )2 ] (Ar=Ph, p-C6 H4 OMe, and p-C6 H4 CF3 ). These species have all been successfully characterized by NMR, IR, and UV/Vis spectroscopy as well as by elemental analysis. Single-crystal X-ray diffraction has verified that these trans-bis(borirene)platinum(II) complexes display coplanarity between the twin three-membered rings across the platinum core in the solid state and stand as the first ex les of coplanar conformations of twin borirene systems. These complexes were modeled using density functional theory (DFT), providing information helpful in determining the ability of the transition metal core to interact with each in idual borirene ring system and allowing for the observed coplanarity of these rings in the solid state. This proposed transition metal interaction with the twin borirene systems is manifested in the electronic characterization of these borirene species, which display ergent photophysical UV/Vis spectroscopic profiles compared to a previously published mono(borirene)platinum(II) complex.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CC07409C
Abstract: The combination of electron-rich diaminoalkynes and ditopic Lewis acids diboranes(4) leads to unusual diboration reactions involving internal Lewis adduct and zwitterion formation and C–C bond formation.
Publisher: Wiley
Date: 06-12-2021
Abstract: Eine Eintopfsynthese eines CAAC‐stabilisierten, unsymmetrischen, cyclischen Diborens wurde mittels Zweielektronenreduktion eines CAAC‐Addukts von B 2 Br 4 (SMe 2 ) 2 entwickelt. Theoretische Studien offenbarten, dass dieses Diboren einen signifikant geringeren HOMO‐LUMO‐Abstand als bisher beschriebene NHC‐ und Phosphan‐stabilisierte Diborene besitzt. Die Komplexierung des Diborens mit [AuCl(PCy 3 )] lieferte zwei Diboren‐Au I ‐π‐Komplexe, während die Reaktion mit DurBH 2 , P 4 und einem terminalen Alkin zur Spaltung der B‐H‐, P‐P‐ beziehungsweise C‐C‐π‐Bindung führte. Die thermische Umlagerung des Diborens ergab ein elektronenreiches cyclisches Alkylidenboran, welches über die B=C‐Doppelbindung direkt an Ag I koordiniert werden konnte.
Publisher: Wiley
Date: 23-03-2022
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CC07371B
Abstract: CuOTf-mediated intramolecular diborene hydroarylation, followed by a σ-bond metathesis between the resulting B–H bond and CuOTf, gives a cyclic sp 2 –sp 3 boryl-substituted boronium triflate.
Publisher: Wiley
Date: 13-07-2023
Abstract: Carbene‐stabilized symmetrical and unsymmetrical dicationic tetraboranes, featuring an electron‐precise tetraborane chain, were synthesized and fully characterized. Reactions of these tetraboranes with reductants/bases give rise to different outcomes according to the conditions employed, including: 1) reduction and rearrangement of the tetraborane chain to give a zwitterionic alkylidene borate–borenium species 2) cleavage of the tetraborane chain to afford a 1,3‐azaborinine and 3) reduction of the supporting ligands to provide a diamino dipotassium salt. The zwitterionic alkylidene borate–borenium species can be viewed as an analogue of the base‐stabilized diborenes. NMR spectroscopy and DFT calculations reveal a highly polarized B−B bond in the zwitterionic alkylidene borate–borenium, in which the formal oxidation states of the boron atoms can be considered as −1 and +2. These results suggest the considerable potential of tetraboranes as synthons for low‐valent boron species.
Publisher: Wiley
Date: 12-10-2016
Abstract: Reduction of carbene-borane adduct [(cAAC)BBr
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8DT04995E
Abstract: AsCl 3 and AsBr 3 are shown to undergo oxidative addition to Pt(0) complexes. With AsCl 3 , a single As–Cl oxidative addition step selectively yields (chloro)(arsenido)-Pt( ii ) complexes, whereas with AsBr 3 both monomeric and cluster compounds are produced.
Publisher: Springer Science and Business Media LLC
Date: 06-2015
DOI: 10.1038/NATURE14489
Abstract: The ability of an atom or molecular fragment to bind multiple carbon monoxide (CO) molecules to form multicarbonyl adducts is a fundamental trait of transition metals. Transition-metal carbonyl complexes are vital to industry, appear naturally in the active sites of a number of enzymes (such as hydrogenases), are promising therapeutic agents, and have even been observed in interstellar dust clouds. Despite the wealth of established transition-metal multicarbonyl complexes, no elements outside groups 4 to 12 of the periodic table have yet been shown to react directly with two or more CO units to form stable multicarbonyl adducts. Here we present the synthesis of a borylene dicarbonyl complex, the first multicarbonyl complex of a main-group element prepared using CO. The compound is additionally stable towards ambient air and moisture. The synthetic strategy used--liberation of a borylene ligand from a transition metal using donor ligands--is broadly applicable, leading to a number of unprecedented monovalent boron species with different Lewis basic groups. The similarity of these compounds to conventional transition-metal carbonyl complexes is demonstrated by photolytic liberation of CO and subsequent intramolecular carbon-carbon bond activation.
Publisher: American Chemical Society (ACS)
Date: 26-03-2014
DOI: 10.1021/OM500111R
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1CC02993B
Abstract: Herein we present a range of new ring expansion reactions of an alumole with heteroatom-containing unsaturated species, providing a range of novel six-, seven- and eight-membered cyclic products with high heteroatom content.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CC06425B
Abstract: The results present a new elimination reaction, the 1,2-alkylborane elimination, as a new route to silylene complexes.
Publisher: Wiley
Date: 22-12-2022
Abstract: Carbene‐stabilized diborynes of the form LBBL (L= N ‐heterocyclic carbene (NHC) or cyclic alkyl(amino)carbene (CAAC)) induce rapid, high yielding, intermolecular ortho‐C−H borylation at N ‐heterocycles at room temperature. A simple pyridyldiborene is formed when an NHC‐stabilized diboryne is combined with pyridine, while a CAAC‐stabilized diboryne leads to activation of two pyridine molecules to give a tricyclic alkylideneborane, which can be forced to undergo a further H‐shift resulting in a zwitterionic, doubly benzo‐fused 1,3,2,5‐diazadiborinine by heating. Use of the extended N ‐heteroaromatic quinoline leads to a borylmethyleneborane under mild conditions via an unprecedented boron‐carbon exchange process.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0DT01181A
Abstract: While the vast majority of inorganic chemistry involves electron donation from main-group atoms to metals, an intriguing yet flip-side exists: where Lewis-basic metals donate electron density to Lewis-acidic main-group atoms (most often boron). These so-called "Z-type" ligands, along with other less clear-cut complexes, are ex les of this metal-ligand role reversal. This perspective article offers an introduction to metal-to-boron dative bonding, and attempts to correlate spectroscopic and structural data from the complexes.
Publisher: Springer Science and Business Media LLC
Date: 29-05-2012
DOI: 10.1038/NCOMMS1884
Abstract: σ-Complexes of transition metals-key intermediates in metal-mediated bond activation and homogeneous catalysis-have traditionally been isolable only when chelating or when one of the participating atoms is hydrogen. Here, by treating the Lewis-basic transition metal complex [Pt(PEt(3))(4)] with an electron-poor borirene, we isolate a complex with an unsupported borirene ligand bound, not through the unsaturated C=C bond, but exclusively via a B-C single bond. Using NMR spectroscopy, X-ray crystallography and density functional theory calculations, we show, herein, that coordination of the borirene ligand is based on electron donation from the B-C σ bond to the metal, aided by a strong Pt-to-B dative interaction. The complex is the first isolable non-agostic σ-complex featuring two p-block elements and has broad implications as a model for the metal-mediated activation of strong p-block-p-block σ-bonds.
Publisher: Wiley
Date: 07-09-2006
Publisher: Springer Science and Business Media LLC
Date: 17-06-2012
DOI: 10.1038/NCHEM.1379
Abstract: Only a handful of elements are able to be controllably homocatenated (that is, to be formed into one- or two-dimensional chains or rings of the element), because most have weak element-element bonds. Boron forms strong B-B bonds, but its favourable cluster formation makes homocatenation very difficult. Recently, the coupling of borylene (:BR) ligands on a metal was predicted computationally. We have brought this prediction to fruition experimentally, and extended it by adding two further borylene units, stepwise forming a B(4) chain bound to a metal under mild conditions. This complex is a useful model for understanding the metal-boron interactions required to promote transition of the boron atoms from borylene ligands to oligoborane networks bound side-on. The concept shows great promise for the controlled construction of one-dimensional boron chains.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5CC07503C
Abstract: The first ex les of borironium cations are prepared by a remarkably mild carbene-induced process. The cations are three-membered unsaturated boron-containing rings with two Lewis donors bound to the boron atom.
Publisher: MDPI AG
Date: 02-2023
DOI: 10.3390/BS13020123
Abstract: There has been growing interest in the social-emotional development of children. However, the social-emotional development of children in Asia remains a knowledge gap. This systematic review identifies and summarizes existing studies on children’s social-emotional development in Asia. We conducted a systematic review using the Guidelines for Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). We reviewed 45 studies that met the inclusion criteria, and they were from 12 Asian countries, primarily the East Asia region (China and Hong Kong). Most of the studies were cross-sectional in design (n = 28, 62.2%). Six themes emerged, including (a) social-emotional development (overall) (n = 24, 53.3%) (b) social competence (n = 7, 15.6%) (c) emotional development (n = 5, 11.1%) (d) social-emotional learning (n = 3, 6.7%) (e) problem behavior (n = 3, 6.7%) (f) self-regulation (n = 2, 4.4%) and (g) both social-emotional learning and problem behavior (n = 1, 2.2%). The findings highlighted the paucity of studies, the need for examining more erse variables in a similar population, and the low quality of intervention studies in social-emotional research in Asia. Research gaps indicate the need for more social-emotional and ethnocultural studies in other Asian regions. Parent and teacher knowledge of children’s social-emotional functioning should be examined more closely in future research.
Publisher: Wiley
Date: 08-07-2016
Abstract: Boryl, borylene, and base-stabilized borylene complexes of manganese and iron undergo a range of different reactions when treated with isonitriles including single, double, and partial isonitrile insertions into metal-boron bonds, ring formation, isonitrile coupling, and the liberation of new monovalent boron species. Two of the resulting cyclic species have also been found to react selectively with anhydrous HCl to form ring-opened products. The erse isonitrile-promoted reactivity of transition-metal-boron compounds has been explored computationally.
Publisher: Wiley
Date: 17-03-2016
Abstract: The construction of single-atom-thick sheets of boron on a silver substrate, which was published in late 2015, represents a significant advance towards the realization of useful two-dimensional materials based solely on boron. This Highlight provides background information on the topic of boron allotropes and an outlook for further work in this area.
Publisher: Wiley
Date: 25-01-2021
Publisher: American Chemical Society (ACS)
Date: 30-06-2014
DOI: 10.1021/JA504761F
Abstract: The first 1,2-additions across a metal-boron double bond are reported, one a definitive chlorogallation of a Fe═B bond, the other a partial chlorogallation of a Mo═B bond that leads to a highly unusual, planar Mo-B-Ga-Cl rhombus. The two reactions occur with opposite regiochemistry, with the Ga atom bound to the Fe atom in the former and to both the Mo and B atoms in the latter. The bonding in the Mo adduct and the reasons for the differing regiochemistry of the reaction are explored computationally.
Publisher: American Chemical Society (ACS)
Date: 22-07-2016
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Holger Braunschweig.