ORCID Profile
0000-0002-9527-6418
Current Organisation
University of St Andrews
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CE00098D
Abstract: Single crystal CPO-27-Mg, -Zn and its structural isomer UTSA-74 have been prepared through use of acid modulators salicylic acid and benzoic acid, respectively.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2SC21298F
Publisher: Elsevier BV
Date: 03-2016
Publisher: Wiley
Date: 04-08-2022
Abstract: Dimagnesium(I) complexes [{( Ar nacnac)Mg} 2 ], where Ar nacnac=HC(MeCNAr) 2 , Ar=Dip=2,6‐ i Pr 2 −C 6 H 3 , Ar=Dep=2,6‐Et 2 −C 6 H 3 , Ar=Mes=2,4,6‐Me 3 −C 6 H 2 , react with iodoarenes in oxidative addition reactions. With iodobenzene, magnesium phenyl and magnesium iodide complex fragments were obtained, and from a reaction with 4‐iodo‐1,2,3,5‐tetramethylpyrazolium iodide, [ Me PZI]I, the pyrazol‐4‐ylidene complex [( Dip nacnac)MgI( Me PZ)] was structurally characterised, alongside other products. The isomeric imidazol‐2‐ylidene complex [( Dip nacnac)MgI( Me NHC)], where Me NHC is 1,3,4,5‐tetramethylimidazol‐2‐ylidene, was prepared and characterised. X‐ray crystal structure determinations and DFT computational studies have been carried out to compare the related complexes. The results show that the Me PZ ligand is higher in energy and more nucleophilic than its more common isomeric Me NHC carbene.
Publisher: Wiley
Date: 14-04-2008
Publisher: Elsevier BV
Date: 10-2016
Publisher: American Chemical Society (ACS)
Date: 31-07-2014
DOI: 10.1021/IC5014768
Abstract: A group of sterically encumbered peri-substituted acenaphthenes have been prepared, containing tin moieties at the 5,6-positions in 1-3 ([Acenap(SnR3)2], Acenap = acenaphthene-5,6-diyl R3 = Ph3 (1), Me3 (2) [(Acenap)2(SnMe2)2] (3)) and phosphorus functional groups at the proximal peri-positions in 4 and 5 ([Acenap(PR2)(P(i)Pr2)] R2 = Ph2 (4), Ph((i)Pr) (5)). Bis(stannane) structures 1-3 are dominated by repulsive interactions between the bulky tin groups, leading to peri-distances approaching the sum of van der Waals radii. Conversely, the quasi-linear CPh-P···P three-body fragments found in bis(phosphine) 4 suggest the presence of a lp(P)-σ*(P-C) donor-acceptor 3c-4e type interaction, supported by a notably short intramolecular P···P distance and notably large JPP through-space coupling (180 Hz). Severely strained bis(sulfides) 4-S and 5-S, experiencing pronounced in-plane and out-of-plane displacements of the exocyclic peri-bonds, have also been isolated following treatment of 4 and 5 with sulfur. The resulting nonbonded intramolecular P···P distances, ∼4.05 Å and ∼12% longer than twice the van der Waals radii of P (3.60 Å), are among the largest ever reported peri-separations, independent of the heteroatoms involved, and comparable to the distance found in 1 containing the larger Sn atoms (4.07 Å). In addition we report two metal complexes with square planar [(4)PtCl2] (4-Pt) and octahedral cis-[(4)Mo(CO)4] (4-Mo) geometries. In both complexes the bis(phosphine) backbone is distorted, but notably less so than in bis(sulfide) 4-S. All compounds were fully characterized, and except for bis(phosphine) 5, crystal structures were determined.
Publisher: Wiley
Date: 11-07-2022
Abstract: The new β‐diketimine i PrDip nacnacH, HC( i PrCNDip) 2 H, Dip=2,6‐ i Pr 2 ‐C 6 H 3 , was converted to the magnesium(I) complex [{( i PrDip nacnac)Mg} 2 ] and reaction with 2‐adamantanone (OAd) afforded the ketone‐1,2‐diide complex [{( i PrDip nacnac)Mg} 2 (μ‐OAd)]. The complex contains the first stable dianion of an aliphatic ketone with an electropositive metal and shows an OAd 2− unit with long C−O bond and pyramidal carbon centre. DFT studies reveal an anionic charge on both neighbouring C and O atoms. Reductions of aliphatic ketones with magnesium(I) complexes show that these likely proceed via highly reactive dianions and afforded a 1 : 1 mixture of an alkoxide and an enolate when an enolisable ketone was used, and rapid CH activations reactions, e.g., of stabilising ligand moieties, when non‐enolisable ketones were employed.
Publisher: Elsevier BV
Date: 2007
Publisher: American Chemical Society (ACS)
Date: 22-01-2014
DOI: 10.1021/JA4123973
Abstract: We report on the design, synthesis, and operation of a bimetallic molecular biped on a three-foothold track. The "walker" features a palladium(II) complex "foot" that can be selectively stepped between 4-dimethylaminopyridine and pyridine ligand sites on the track via reversible protonation while the walker remains attached to the track throughout by means of a kinetically inert platinum(II) complex foot. The substitution pattern of the three ligand binding sites, together with the kinetic stability of the metal-ligand coordination bonds, affords the two positional isomers a high degree of metastability, meaning that altering the chemical state of the track does not automatically instigate stepping in the absence of an additional stimulus (heat in the presence of a coordinating solvent). The use of metastable metal complexes for foot-track interactions offers a promising alternative to dynamic covalent chemistry for the design of small-molecule synthetic molecular walkers.
Publisher: Wiley
Date: 30-10-2015
Abstract: The ionothermal synthesis, structure, and magnetic susceptibility of a novel inorganic–organic hybrid material, imidazolium vanadium(III,IV) oxyfluoride [C 3 H 5 N 2 ][V 9 O 6 F 24 (H 2 O) 2 ] (ImVOF) are presented. The structure consists of inorganic vanadium oxyfluoride slabs with kagome layers of V 4+ S = ions separated by a mixed valence layer. These inorganic slabs are intercalated with imidazolium cations. Quinuclidinium (Q) and pyrazinium (Pyz) cations can also be incorporated into the hybrid structure type to give QVOF and PyzVOF analogues, respectively. The highly frustrated topology of the inorganic slabs, along with the quantum nature of the magnetism associated with V 4+ , means that these materials are excellent candidates to host exotic magnetic ground states, such as the highly sought quantum spin liquid. Magnetic susceptibility measurements of all s les suggest an absence of conventional long‐range magnetic order down to 2 K despite considerable antiferromagnetic exchange.
Publisher: Wiley
Date: 16-12-2013
Abstract: A new structural arrangement Te3 (RP(III) )3 and the first crystal structures of organophosphorus(III)-tellurium heterocycles are presented. The heterocycles can be stabilized and structurally characterized by the appropriate choice of substituents in Tem (P(III) R)n (m=1: n=2, R=OMes* (Mes*=supermesityl or 2,4,6-tri-tert-butylphenyl) n=3, R=adamantyl (Ad) n=4, R=ferrocene (Fc) m=n=3: R=trityl (Trt), Mesor by the installation of a P(V) 2 N2 anchor in RP(III) [TeP(V) (tBuN)(μ-NtBu)]2 (R=Ad, tBu).
Publisher: Frontiers Media SA
Date: 02-08-2021
DOI: 10.3389/FCHEM.2021.728845
Abstract: [2.2]Paracyclophane scaffolds have seen limited use as building blocks in supramolecular chemistry. Here, we report the synthesis and characterization of a 1D coordination polymer consisting of silver(I) ions bound to a [2.2]paracyclophane scaffold functionalized with two 4-pyridyl units. The structure of the polymer has been determined from single crystal X-ray diffraction analysis and reveals two different silver coordination motifs that alternate along the 1D coordination polymer. The coordination polymer exhibits strong blue and sky-blue fluorescence in solution and in the crystalline solid state, respectively.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CC01073F
Abstract: Reaction of Woollins' reagent ( WR ) with pyridine yields the P(V) species PhPSe 2 stabilised by pyridine coordination. Its potential as a selenation reagent under mild conditions was shown by calculations and an experimental comparison to WR .
Publisher: American Chemical Society (ACS)
Date: 24-09-2012
DOI: 10.1021/IC301627Y
Abstract: Twelve related monocation chalconium salts [{Nap(EPh)(E'Ph)Me}(+){CF(3)SO(3)}(-)] 2-4, [{Acenap(Br)(EPh)Me}{CF(3)SO(3)}(-)] 5-7, and [{Acenap(EPh)(E'Ph)Me}(+){CF(3)SO(3)}(-)] 8-13 have been prepared and structurally characterized. For their synthesis naphthalene compounds [Nap(EPh)(E'Ph)] (Nap = naphthalene-1,8-diyl E/E' = S, Se, Te) N2-N4 and associated acenaphthene derivatives [Acenap(X)(EPh)]/[Acenap(EPh)(E'Ph)] (Acenap = acenaphthene-5,6-diyl E/E' = S, Se, Te X = Br) A5-A13 were independently treated with a single molar equivalent of methyl trifluoromethanesulfonate (MeOTf). In addition, reaction of bis-tellurium compound A10 with 2 equiv of MeOTf afforded the doubly methylated dication salt [{Acenap(TePhMe)(2)}(2+){(CF(3)SO(3))(2)}(2-)}] 14. The distortion of the rigid naphthalene and acenaphthene backbone away from ideal was investigated in each case and correlated in general with the steric bulk of the interacting atoms located at the proximal peri positions. Naturally, introduction of the ethane linker in acenaphthene compounds increased the splay of the bay region compared with equivalent naphthalene derivatives resulting in greater peri distances. The conformation of the aromatic rings and subsequent location of p-type lone pairs has a significant impact on the geometry of the peri region, with anomalies in peri separations correlated to the ability of the frontier orbitals to take part in attractive or repulsive interactions. In all but one of the monocations a quasi-linear three-body C(Me)-E···Z (E = Te, Se, S Z = Br/E) fragment provides an attractive component for the E···Z interaction. Density functional studies confirmed these interactions and suggested the onset of formation of three-center, four-electron bonding under appropriate geometric conditions, becoming more prevalent as heavier congeners are introduced along the series. The increasingly large J values for Se-Se, Te-Se, and Te-Te coupling observed in the (77)Se and (125)Te NMR spectra for 1, 3, 4, 9, 10, and 13 give further evidence for the existence of a weakly attractive through-space interaction.
Publisher: Georg Thieme Verlag KG
Date: 03-02-2015
Publisher: American Chemical Society (ACS)
Date: 09-06-2014
DOI: 10.1021/IC500697M
Abstract: The reactions of peri-substitution-stabilized phosphanylidene-phosphorane 1 with [AuCl(tht)] or [PtCl2(cod)] afford binuclear complexes [((1)(AuCl)2)2] 2 and [((1)(PtCl2))2] 3, in which four electrons of the ligand are used in bonding to two metal atoms in the bridging arrangement. Reactions of 1 with [Mo(CO)4(nbd)] or (RhCl2Cp*)2 afford mononuclear complexes [(1)2Mo(CO)4] 4 and [(1)RhCl2Cp*] 5, in which two electrons of the ligand are used to form terminal complexes. Formation of these complexes disrupts the negative hyperconjugation at the P-P bond to various extents, which is mirrored by variations in their P-P bond distances (2.179(4)-2.246(4) Å). The P-P bond is ruptured upon formation of Pd diphosphene complex 6, which is likely to proceed through a phosphinidene intermediate. In air, 1 is fully oxidized to phosphonic acid 7. Reactions of 1 with chalcogens under mild conditions generally afford mixtures of products, from which the trithionated 8, dithionated 9, diselenated 10, and monotellurated 11 species were isolated. The bonding in the chalcogeno derivatives is discussed using DFT (B3LYP) and natural bond orbital analysis, which indicate a contribution from dative bonding in 8-10. The buttressing effect of the peri backbone is shown to be an essential factor in the formation of the single push-double-pull bis(borane) 13. This is demonstrated experimentally through a synthesis parallel to that used to make 13, but lacking the backbone, which leads to different products. The P-P bond distances in the reported products, as well as additional species, are correlated with Wiberg bond indices, showing very good agreement for a variety of bonding modes, including the negative hyperconjugation.
Publisher: American Chemical Society (ACS)
Date: 10-02-2010
DOI: 10.1021/JM901660C
Abstract: Following the recent discovery and development of 2-anilino-4-(thiazol-5-yl)pyrimidine cyclin dependent kinase (CDK) inhibitors, a program was initiated to evaluate related ring-constrained analogues, specifically, 2-methyl- and 2-amino-N-aryl-4,5-dihydrothiazolo[4,5-h]quinazolin-8-amines for inhibition of CDKs. Here we report the rational design, synthesis, structure-activity relationships (SARs), and cellular mode-of-action profile of these second generation CDK inhibitors. Many of the analogues from this chemical series inhibit CDKs with very low nanomolar K(i) values. The most potent compound reported in this study inhibits CDK2 with an IC(50) of 0.7 nM ([ATP] = 100 microM). Furthermore, an X-ray crystal structure of 2-methyl-N-(3-(nitro)phenyl)-4,5-dihydrothiazolo[4,5-h]quinazolin-8-amine (11g), a representative from the chemical series in complex with cyclin A-CDK2, is reported, confirming the design rationale and expected binding mode within the CDK2 ATP binding pocket.
Publisher: American Chemical Society (ACS)
Date: 02-10-2014
DOI: 10.1021/OM500755W
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CC12720A
Abstract: Oxime carbonates were found to be excellent precursors for the clean and direct generation of iminyl radicals under UV irradiation. Suitably functionalised iminyls underwent cyclisations yielding various phenanthridines and also substituted quinolines and isoquinolines. EPR and X-ray analyses of oxime carbonates provided insight into the mechanism.
Publisher: Wiley
Date: 15-10-2018
Abstract: High-efficiency pure blue phosphorescent organic light-emitting diodes (OLEDs) remain one of the grand challenges, principally because the emissive complexes employed either do not possess sufficiently high photoluminescence quantum yields or exhibit unsatisfactory Commission International de l'Éclairage (CIE) coordinates. Here two deep-blue-emitting homoleptic iridium(III) complexes are reported and OLEDs are demonstrated with CIE coordinates of (0.15, 0.05) and maximum external quantum efficiency of 13.4%, which decreases slightly to 12.5% at 100 cd m
Publisher: American Chemical Society (ACS)
Date: 07-2021
Publisher: Wiley
Date: 24-07-2017
Abstract: Halogenated analogues of the neurotoxic alkaloid muscimol were prepared with fluorine, iodine or trifluoromethyl at the 4 position of the isoxazole ring system. These compounds were investigated as agonists for GABA
Publisher: MDPI AG
Date: 28-11-2021
DOI: 10.3390/MOLECULES26237214
Abstract: The reaction of [{(Arnacnac)Mg}2] (Arnacnac = HC{MeC(NAr)}2, Ar = 2,6-diisopropylphenyl, Dip, or 2,6-diethylphenyl, Dep) with 4-dimethylaminopyridine (DMAP) at elevated temperatures afforded the hexameric magnesium 4-pyridyl complex [{(Arnacnac)Mg(4-C5H4N)}6] via reductive cleavage of the DMAP C-N bond. The title compound contains a large s-block organometallic cyclohexane-like ring structure comprising tetrahedral (Arnacnac)Mg nodes and linked by linear 4-pyridyl bridging ligands, and the structure is compared with other ring systems. [(Dipnacnac)Mg(DMAP)(NMe2)] was structurally characterised as a by-product.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C2DT32716C
Abstract: Oxidation of alkali metal derivatives of [Te((t)BuN)P(μ-N(t)Bu)(2)P(N(t)Bu)Te](2-) with I(2) produces the intermediate ditelluride dianion [Te((t)BuN)P(μ-N(t)Bu)(2)P(N(t)Bu)Te](2)(2-) with a planar PTeTeP conformation and, subsequently, the cyclic tritelluride [((t)BuN)P(μ-N(t)Bu)(2)P(N(t)Bu)(μ-TeTeTe)].
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2OB26402A
Abstract: Three selectively fluorinated cinacalcet analogues are prepared and their activity as calcium-sensing receptor (CaR) agonists is assessed. In idual (2R,1'R)-2 and (2S,1'R)-3 fluorocinacalcet diastereoisomers were prepared using the MacMillan asymmetric fluorination reaction. Assays with the recombinant human CaR revealed that both diastereoisomers have a similar potency to each other although slightly lower (75-80%) than that of cinacalcet 1. The SF(5)-cinacalcet analogue 4 was prepared from meta-pentafluorosulfanyl benzyl alcohol and has ~75% agonist activity relative to cinacalcet 1 indicating that the SF(5) group can replace the CF(3) group and retain significant bioactivity.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2DT12031C
Abstract: Sterically crowded peri-substituted selenium and tellurium acenaphthene donors D1-D7 [Acenap(EPh)(Br) E = Se, Te Acenap(SePh)(EPh) E = Se, S Acenap(TePh)(EPh) E = S, Se, Te] react with dibromine and diiodine acceptors to afford a group of structurally erse addition products 1-12, comparable in some cases to previously reported naphthalene analogues. Tellurium donors D4-D6 react conventionally with the dihalogens to afford insertion adducts 6-11 (X-R(2)Te-X) exhibiting molecular see-saw geometries, characterised by hypervalent X-Te-X quasi-linear fragments. The reactions of selenium donors D1-D3 with diiodine afford expected neutral charge-transfer (CT) spoke adducts 1, 4 and 5 (R(2)Se-I-I) containing quasi-linear Se-I-I alignments. Conversely, treatment of D2 and D3 with dibromine results in the formation of two tribromide salts 2 and 3 containing bromoselanyl cations [R(2)Se-Br](+)···[Br-Br(2)](-), each exhibiting a quasi-linear three-body Br-Se···E (E = Se, S) fragment. The peri-bonding in these species can be thought of as a weak hypervalent G···Se-X three-centre, four-electron (3c-4e) type interaction, closely related to the T-shaped 3c-4e interaction. Density-functional calculations performed on 2 and 3 and their bare cations (2a and 3a) reveal Wiberg bond indices of 0.25-0.37, suggesting substantial 3c-4e character in these systems. The presence of such an interaction operating in 2 and 3 alleviates steric strain within the peri-region and minimises the degree of molecular distortion required to achieve a relaxed geometry. Ditellurium donor D7 reacts with dibromine to afford an unorthodox insertion adduct 12 containing a Te-O-Te bridge and two quasi-linear Br-Te-O fragments, with the central tellurium atoms assuming a molecular see-saw geometry. Whilst DFT calculations indicate 12 is thermodynamically unfavourable, its formation is viable under experimental conditions.
Publisher: American Chemical Society (ACS)
Date: 27-03-2013
DOI: 10.1021/IC3024875
Abstract: Coupling of two acenaphthene backbones through a phosphorus atom in a geminal fashion gives the first geminally bis(peri-substituted) tridentate phosphine 1. The rigid nature of the aromatic backbone and overall crowding of the molecule result in a rather inflexible ligand, with the three phosphorus atoms forming a relatively compact triangular cluster. Phosphine 1 displays restricted dynamics on an NMR time scale, which leads to the anisochronicity of all three phosphorus nuclei at low temperatures. Strained bis- and tris(sulfides) 2 and 3 and the bis(selenide) 4 have been isolated from the reaction of 1 with sulfur and selenium, respectively. These chalcogeno derivatives display pronounced in-plane and out-of-plane distortions of the aromatic backbones, indicating the limits of their angular distortions. In addition, we report metal complexes with tetrahedral [(1)Cu(MeCN)][BF4] (5), square planar [(1)PtCl][Cl] (6), trigonal bipyramidal [(1)FeCl2] (7), and octahedral fac-[(1)Mo(CO)3] (8) geometries. In all of these complexes the tris(phosphine) backbone is distorted, however to a significantly smaller extent than that in the mentioned chalcogenides 2-4. Complexes 5 and 8 show fluxionality in (31)P and (1)H NMR. All new compounds 1-8 were fully characterized, and their crystal structures are reported. Conclusions from dynamic NMR observations were augmented by DFT calculations.
Publisher: American Chemical Society (ACS)
Date: 08-05-2014
DOI: 10.1021/OM500289B
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5DT02924D
Abstract: Four different coordination polymers were prepared by reaction of Zn(OAc) 2 and 5-methoxy isophthalic acid using various aqueous/aqueous alcohol solvent systems.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9SC03857D
Abstract: Fullerene C 60 reacts with dimagnesium( i ) compounds LMgMgL, where L is a monoanionic β-diketiminate ligand, to contact ion complexes [(LMg) n C 60 ], where n is predominantly 2, 4 or 6.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C2DT31971C
Abstract: Reaction chemistry of an extremely sterically encumbered phosphinic chloride (Mes*)(2)P(=O)Cl (Mes* = 2,4,6-tri-t-butylphenyl, supermesityl) was investigated. This compound, as well as other compounds bearing two supermesityl groups placed geminally at the central phosphorus atom, shows extremely low reactivity at the phosphorus centre. Nevertheless, some synthetically significant transformations were possible. Reduction with hydridic reagents under forcing conditions yielded the phosphine oxide (Mes*)(2)P(=O)H and a secondary phosphine Mes*(2,4-tBu(2)C(6)H(3))PH. Deprotonation of (Mes*)(2)P(=O)H gave the corresponding phosphinite, which afforded very crowded tertiary phosphine oxides (Mes*)(2)P(=O)R (R = Me and Et) on reactions with electrophiles. While the reaction of the phosphine Mes*(2,4-tBu(2)C(6)H(3))PH with sulfur was surprisingly facile (although under forcing conditions), we have been unable to chlorinate or deprotonate this phosphine. All new compounds were fully characterised with multinuclear NMR, IR, Raman, MS, microanalyses and single crystal X-ray diffraction. Our computations (B3LYP and M06-2X level) show that strain energies of (synthetically accessible) geminally substituted compounds are extremely high (180 to 250 kJ mol(-1)), the majority of the strain is stored as boat distortions to the phenyl rings in Mes* substituents.
Publisher: American Chemical Society (ACS)
Date: 19-07-2011
DOI: 10.1021/JA2049786
Abstract: We report on the use of the hydrogen bond acceptor properties of some phosphorus-containing functional groups for the assembly of a series of [2]rotaxanes. Phosphinamides, and the homologous thio- and selenophosphinamides, act as hydrogen bond acceptors that, in conjunction with an appropriately positioned amide group on the thread, direct the assembly of amide-based macrocycles around the axle to form rotaxanes in up to 60% yields. Employing solely phosphorus-based functional groups as the hydrogen bond accepting groups on the thread, a bis(phosphinamide) template and a phosphine oxide-phosphinamide template afforded the corresponding rotaxanes in 18 and 15% yields, respectively. X-ray crystallography of the rotaxanes shows the presence of up to four intercomponent hydrogen bonds between the amide groups of the macrocycle and various hydrogen bond accepting groups on the thread, including rare ex les of amide-to-phosphinamide, -thiophosphinamide, and -selenophosphinamide groups. With a phosphine oxide-phosphinamide thread, the solid-state structure of the rotaxane is remarkable, featuring no direct intercomponent hydrogen bonds but rather a hydrogen bond network involving water molecules that bridge the H-bonding groups of the macrocycle and thread through bifurcated hydrogen bonds. The incorporation of phosphorus-based functional groups into rotaxanes may prove useful for the development of molecular shuttles in which the macrocycle can be used to hinder or expose binding ligating sites for metal-based catalysts.
Publisher: American Chemical Society (ACS)
Date: 20-08-2014
DOI: 10.1021/JO5015678
Abstract: The synthesis of rigid symmetric polyradical model systems with inter-spin distances between 1.4 and 4 nm and their room temperature continuous wave (CW) EPR spectra are reported. Conditions for attachment of the spin-label via esterification have been optimized on the direct synthesis of polyradicals from commercially available polyphenols and the carboxylic acid functionalized nitroxide TPC. A common synthetic protocol utilizing 4-hydroxy-4'-iodobiphenyl as a key building block has been used to synthesize an equilateral biradical and a triradical in only two steps from commercially available starting materials. The first synthesis of a tetraradical based upon an adamantane core bearing six equivalent nitroxide-nitroxide distances is also reported. These systems are very promising candidates for studying multi-spin effects in pulsed EPR distance measurements.
Publisher: Wiley
Date: 22-12-2014
Abstract: Three related series of peri-substituted bis(tellurides) bearing naphthalene, acenaphthene and acenaphthylene backbones (Nap/Acenap/Aceyl(TeY)2 (Nap = naphthalene-1,8-diyl N Acenap = acenaphthene-5,6-diyl A Aceyl = acenaphthylene-5,6-diyl Ay Y = Ph 1 Fp 2 Tol 3 An-p- 4 An-o- 5 Tp 6 Mes 7 Tip 8) have been synthesised and their solid-state structures determined by X-ray crystallography. Molecular conformations were classified as a function of the two C9-C-Te-C(Y) dihedral angles (θ) in the solid all members adopt AB or CCt configurations, with larger Te(aryl) moieties exclusively imposing the CCt variant. Exceptionally large J((125)Te,(125)Te) spin-spin coupling constants between 3289-3848 Hz were obtained for compounds substituted by bulky Te(aryl) groups, implying these species are locked in a CCt-type conformation. In contrast, compounds incorporating smaller Te(aryl) moieties are predicted to be rather dynamic in solution and afford much smaller J values (2050-2676 Hz), characteristic of greater populations of AB conformers with lower couplings. This conformational dependence of through-space coupling is supported by DFT calculations.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5CE02091C
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3DT52385C
Abstract: There are only limited reports on vanadium(iv) oxyfluorides (VOFs) with extended crystal structures. Here we expand and enrich the list of existing VOFs with a series of 14 new materials "VOF-n (n = 1-14)" prepared using ionothermal and solvothermal synthesis methods. All of these materials arise from the condensation of a dimeric structural motif. These VOFs can be classified into three groups depending on their key structural features layer structures: VOF-1"[HN2C7H6][V2O2F5]", VOF-2"[HN2C4H4][V2O2F5]", VOF-3"[HN2C3H4][V2O2F5]" and VOF-4"V2(N2C4H4)O2F4", ladder like structures: VOF-5"[NH4(HN2C3H4)][V2O2F6]", VOF-6"[K(HN2C3H4)][V2O2F6]", VOF-7"[HNH2CH2CH3][VOF3]", VOF-8"[HN2C7H6][VOF3]", VOF-9"[H2N2C4H6][V2O2F6]", VOF-10"β-RbVOF3", VOF-11"α-KVOF3", VOF-12"β-KVOF3", VOF-13"[H2(NH2)2(CH2)2][V2O2F6]", and a chain structure: VOF-14"[H2N2C6H12][V2O2F7]". The crystal structures of VOF-n are presented, and their synthetic and structural relationships are discussed.
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B712188A
Abstract: Reaction of MnCl(2).4H(2)O with H(3)L (H(3)L = tris(6-hydroxymethyl-2-pyridylmethyl)amine) in methanol gives hepta-coordinated [Mn(H(3)L)]Cl(2) involving attachment of Mn(II) to all four nitrogens and three hydroxymethyl arms. Reaction of H(3)L with Fe(ClO(4))(2).6H(2)O in CH(3)CN in the presence of NaO(2)CC(6)H(5) in an attempt to make [Fe(III)OH(H(3)L)(O(2)CC(6)H(5))](ClO(4)), a putative model for soybean lipoxygenase-1, instead gave rise to the linear triiron(III) complex [Fe(3)L(2)](ClO(4))(3) with all three hydroxymethyl arms deprotonated and forming three alkoxide bridges between each Fe(III) centre. The central Fe(III) is hexa-coordinated to only the alkoxide bridges and flanked by two hepta-coordinated iron(III) centres analogous to the Mn(ii) complex. [Fe(3)L(2)](ClO(4))(3) exhibits two reversible 1e(-) reductions to mixed-valence [Fe(3)L(2)](2+) and [Fe(3)L(2)](+) forms. Structure data and magnetochemistry on [Fe(3)L(2)](ClO(4))(3) reveals the tightest Fe-O-Fe angle (87.4 degrees ) and shortest Fe...Fe distance (2.834 A) yet found for any weakly antiferromagnetically-coupled high spin alkoxide-bridged di- or triiron(iii) system and challenges current theories involved in correlating the extent/nature of magnetic interactions in such systems based on Fe-O(bridge) distances and Fe-O-Fe angles. The central hexa-alkoxide coordinated Fe(III) is novel and shows a remarkable resistance towards reduction to Fe(II).
Publisher: American Chemical Society (ACS)
Date: 23-12-2019
DOI: 10.1021/ACS.ORGLETT.9B04404
Abstract: The use of silyl nitronates is reported for the isothiourea-catalyzed synthesis of γ-nitro-substituted silyl esters containing up to two contiguous stereocenters in good yields with excellent enantioselectivities (up to 93% yield and 99:1 er). The serendipitously discovered formation of silyl ester products in this reaction demonstrates a novel platform for catalyst turnover in α,β-unsaturated acyl ammonium catalysis.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9DT03976G
Abstract: Exchange of anionic ligands on the Mg 2 2+ ion via an associative mechanism can be facile and depends on ligand sterics and shape.
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B615378J
Abstract: A series of ansa-quinones has been prepared by chemical synthesis, and evaluated by biological techniques. Thus, 19-membered ansa-lactams, simplified analogues of the naturally occurring Hsp90 molecular chaperone inhibitor geldanamycin, were obtained by concise routes, the key steps being the combination of a ring-closing metathesis to give a 17-membered ring followed by Claisen rearrangement to effect ring expansion. The methodology was also used to prepare an "unnatural" 18-membered ring analogue. In ATPase enzyme assays, the synthetic ansa-quinones were weak inhibitors of Hsp90.
Publisher: MDPI AG
Date: 24-12-2017
DOI: 10.3390/CRYST8010006
Publisher: American Chemical Society (ACS)
Date: 07-09-2016
Publisher: Wiley
Date: 27-03-2015
Abstract: A series of phosphine-stibine and phosphine-stiborane peri-substituted acenaphthenes containing all permutations of pentavalent groups -SbCln Ph4-n (5-9), as well as trivalent groups -SbCl2 , -Sb(R)Cl, and -SbPh2 (2-4, R=Ph, Mes), were synthesised and fully characterised by single crystal diffraction and multinuclear NMR spectroscopy. In addition, the bonding in these species was studied by DFT computational methods. The P-Sb dative interactions in both series range from strongly bonding to non-bonding as the Lewis acidity of the Sb acceptor is decreased. In the pentavalent antimony series, a significant change in the P-Sb distance is observed between -SbClPh3 and -SbCl2 Ph2 derivatives 6 and 7, respectively, consistent with a change from a bonding to a non-bonding interaction in response to relatively small modification in Lewis acidity of the acceptor. In the Sb(III) series, two geometric forms are observed. The P-Sb bond length in the SbCl2 derivative 2 is as expected for a normal (rather than a dative) bond. Rather unexpectedly, the phosphine-stiborane complexes 5-9 represent the first ex les of the σ(4) P→σ(6) Sb structural motif.
Publisher: American Chemical Society (ACS)
Date: 05-03-2012
DOI: 10.1021/OM201253T
Publisher: Wiley
Date: 24-02-2014
Publisher: Informa UK Limited
Date: 03-03-2016
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B924143D
Abstract: The syntheses, structures and magnetic properties of nine new iron complexes containing salicylaldoxime (saoH(2)) or derivatised salicylaldoximes (R-saoH(2)), [Fe(3)O(OMe)(Ph-sao)(2)Cl(2)(py)(3)].2MeOH (1.2MeOH), [Fe(3)O(OMe)(Ph-sao)(2)Br(2)(py)(3)].Et(2)O (2.Et(2)O), [Fe(4)(Ph-sao)(4)F(4)(py)(4)].1.5MeOH (3.1.5MeOH), [Fe(6)O(2)(OH)(2)(Et-sao)(2)(Et-saoH)(2)(O(2)CPh)(6)] (4), [HNEt(3)](2)[Fe(6)O(2)(OH)(2)(Et-sao)(4)(O(2)CPh(Me)(2))(6)].2MeCN (5.2MeCN), [Fe(6)O(2)(O(2)CPh)(10)(3-(t)But-5-NO(2)-sao)(2)(H(2)O)(2)].2MeCN (6.2MeCN), [Fe(6)O(2)(O(2)CCH(2)Ph)(10)(3-(t)But-sao)(2)(H(2)O)(2)].5MeCN (7.5MeCN), {[Fe(6)Na(3)O(OH)(4)(Me-sao)(6)(OMe)(3)(H(2)O)(3)(MeOH)(6)].MeOH}n (8.MeOH) and [HNEt(3)](2)[Fe(12)Na(4)O(2)(OH)(8)(sao)(12)(OMe)(6)(MeOH)(10)] (9) are discussed. The predominant building block appears to be the triangular [Fe(3)O(R-sao)(3)](+) species which can self-assemble into more elaborate arrays depending on reaction conditions. An interesting observation is that the R-saoH(-)/R-sao(2-) ligand system tends to adopt coordination modes similar to carboxylates. The most unusual molecule is the [Fe(4)F(4)] molecular square, 3. While Cl(-) and Br(-) appear to act only as terminal ligands, the F(-) ions bridge making a telling impact on molecular structure and topology.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5RA27594F
Abstract: The fundamental synthetic building blocks FcPH 2 and FcPCl 2 are obtained in high yield and excellent purities via the fully regiospecific electrophilic monofunctionalisation of ferrocene with P 4 S 10 , thus replacing inconvenient t BuLi based procedures.
Publisher: Wiley
Date: 28-11-2022
Abstract: Four new deep‐blue‐emitting iridium(III) NHC complexes containing sterically demanding ligands are synthesized. The four complexes show bright, deep‐blue emission, with emission maxima between 420 and 427 nm in both acetonitrile solution and 30 wt% doped films in TSPO1 the two meridional isomers showing photoluminescence quantum yields, Φ PL , in doped films of 80% and 89%. The two meridional isomers are used to assess the impact of emitters containing bulky, sterically demanding ligands on the performance of organic light‐emitting diodes (OLEDs). OLEDs employing a stepped doping profile with mer ‐Ir(tfpi_tmBn) 3 as the emitter produce the highest performing devices in this study, with these devices exhibiting deep‐blue [λ EL = 429 nm, CIE = (0.16, 0.08)] emission and a maximum external quantum efficiency (EQE max ) of 14.9%, which decreases to 11.7% at 100 cd m −2 . The performance of the OLEDs shows very good efficiencies and moderate efficiency roll‐offs in comparison to reported phosphorescent deep‐blue OLEDs with CIE y ≤ 0.08, as required for commercial displays. The promising results suggest that the design strategy of adding steric bulk to blue emitting iridium complexes containing NHC ligands is a useful strategy for reducing intermolecular interactions between emitters in OLEDs.
Publisher: Wiley
Date: 12-10-2015
Abstract: The synthesis and characterization of abnormal N‐heterocyclic carbene, cyclic (alkyl)(amino)carbene, and mesoionic carbene copper(I) complexes are reported. These organometallic species are obtained via a versatile and inexpensive synthetic pathway using readily available reactants, namely copper oxide and iminium salts. The catalytic activity of this series of complexes was evaluated in the [3+2] cycloaddition of alkynes with azides (CuAAC). Outstanding catalytic properties were observed for the abnormal NHC‐ and triazolylidene‐based copper(I) complexes. magnified image
Publisher: Wiley
Date: 24-09-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9DT00841A
Abstract: New [Au(IPr)(CHR 2 )] complexes have been synthesised through protonolysis reactions of [Au(IPr)(OH)] with moderately acidic substrates, CH 2 R 2 .
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8DT01798K
Abstract: Sterically demanding NHC aluminium hydride iodide complexes react with one equivalent of NHC to cationic mixed normal – abnormal NHC Al III complexes.
Publisher: Wiley
Date: 13-11-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5DT02542G
Abstract: Subtle changes in the structure of the backbone can lead to profound differences in the binding modes of dithiolato ligands in rhodium and iridium half sandwich complexes.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3SC50500F
Publisher: American Chemical Society (ACS)
Date: 26-02-2015
DOI: 10.1021/ACS.INORGCHEM.5B00161
Abstract: A comprehensive investigation of reactions of alkali-metal derivatives of the ditelluro dianion [TePV(NtBu)(μ-NtBu)]22– (L2–, E = Te) with p-block element halides produced a series of novel heterocycles incorporating P2VN2 rings, tellurium, and group 13–16 elements. The dianion engages in Te,Te′-chelation to the metal center in Ph2Ge and R2Sn (R = tBu, nBu, Ph) derivatives similar behavior was noted for group 14 derivatives of L2– (E = S, Se). In the case of group 13 trihalides MCl3 (M = Ga, In), neutral spirocyclic complexes (L)M[NtBu(Te)PV(μ-NtBu)2PIIIN(H)tBu)] (M = Ga, In) comprised of a Te,Te′-chelated ligand L2– and a N,Te-bonded ligand resulting from loss of Te and monoprotonation were obtained. In reactions with RPCl2 (R = tBu, Ad, iPr2N) a significant difference was observed between Se- and S-containing systems. In the former case, Se,Se′-chelated derivatives were formed in high yields, whereas the N,S-chelated isomers predominated for sulfur. All complexes were characterized by multinuclear (1H, 31P, 77Se, 119Sn, and 125Te) NMR spectroscopy this technique was especially useful in the analysis of the mixture of (L)(Se) and (L)(SeSe) obtained from the reaction of Se2Cl2 with L2– (E = Te). Single-crystal X-ray structures were obtained for the spirocyclic In complex (9), (L)GePh2 (E = Te, 10), (L)SntBu2 (E = Te, 12a) E = Se, 12aSe, E = S, 12aS) and (L)(μ-SeSe) (E = Te, 16).
Publisher: American Chemical Society (ACS)
Date: 18-02-2015
DOI: 10.1021/IC503056Z
Abstract: A series of peri-substituted phosphorus-tellurium systems R'Te-Acenap-PR2 (R' = Ph, p-An, Nap, Mes, Tip Acenap = acenaphthene-5,6-diyl (-C12H8) R = (i)Pr, Ph) exhibiting large "through-space" spin-spin coupling constants and the "onset" of three-center four-electron type interactions is presented. The influence of the substituents at the phosphorus and tellurium atoms as well as their behavior upon oxidation (with S, Se) or metal-coordination (Pt, Au) is discussed using NMR spectroscopy, single-crystal X-ray diffraction, and advanced density functional theory studies including NBO, AIM, and ELI-D analyses.
Publisher: Wiley
Date: 27-08-2008
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4DT03257H
Abstract: The versatile coordinating ability of a novel spirocyclic, P 2 N 2 -supported Te 5 dianion is exemplified by N , N ′-bonding to Na + ions and Te,Te′,Te′′ linkages to a Cp*Rh( iii ) group.
Publisher: American Chemical Society (ACS)
Date: 24-02-2009
DOI: 10.1021/JA809627J
Abstract: The synthesis of catenanes and rotaxanes using the hard trivalent transition metal ion cobalt(III) as a template is reported. Tridentate dianionic pyridine-2,6-dicarboxamido ligands, each with two terminal alkene groups, coordinate Co(III) in a mutually orthogonal arrangement such that entwined or interlocked molecular architectures are produced by ring-closing olefin metathesis. Double macrocyclization of two such ligands bound to Co(III) afford a non-interlocked "figure-of-eight" complex in 42% yield, the structure determined by X-ray crystallography. Preforming one macrocycle and carrying out a single macrocyclization of the second bis-olefin with both ligands attached to the Co(III) template led to the isomeric [2]catenate in 69% yield. The mechanically interlocked structure was confirmed by X-ray crystallography of both the Co(III) catenate and the metal-free catenand. A Co(III)-template [2]rotaxane was assembled in 61% yield by macrocyclization of the bis-olefin ligand about an appropriate dianionic thread. For both catenanes and rotaxanes, removal of the metal ion via reduction under acidic conditions to the more labile Co(II) gave neutral interlocked molecules with well-defined co-conformations stabilized by intercomponent hydrogen bonding.
Publisher: American Chemical Society (ACS)
Date: 05-05-2015
DOI: 10.1021/JACS.5B03353
Abstract: Solid-state NMR spectra of new P-Se heterocycles based on peri-substituted naphthalene motifs show the presence of unusual J couplings between Se and P. These couplings are between atoms in adjacent molecules and occur "through space", rather than through conventional covalent bonds. Experimental measurements are supported by relativistic DFT calculations, which confirm the presence of couplings between nonbonded atoms, and provide information on the pathway of the interaction. This observation improves the understanding of J couplings and offers insight into the factors that affect crystal packing in solids, for future synthetic exploitation.
Publisher: Elsevier BV
Date: 2009
Publisher: American Chemical Society (ACS)
Date: 29-07-2014
DOI: 10.1021/IC501142V
Abstract: Coordination chemistry of an acenaphthene peri-backbone-supported phosphino-phosphonium chloride (1) was investigated, revealing three distinct modes of reactivity. The reaction of 1 with Mo(CO)4(nor) gives the Mo(0) complex [(1)Mo(CO)4Cl] (2), in which the ligand 1 exhibits monodentate coordination through the phosphine donor and the P-P bond is retained. PtCl2(cod) reacts with the chloride and triflate salts of 1 to form a mononuclear complex [(1Cl)PtCl2] (3) and a binuclear complex [((1Cl)PtCl)2][2TfO] (4), respectively. In both of these complexes, the platinum center adds across the P-P bond, and subsequent chloride transfer to the phosphenium center results in phosphine-chlorophosphine bidentate coordination. [((1)PdCl)2] (5) was isolated from the reaction of 1 and Pd2(dba)3 (dba = dibenzylideneacetone). Oxidative addition to palladium(0) results in a heteroleptic phosphine bridging phosphide coordination to the Pd(II) center. In addition, reaction of 1 with BH3·SMe2 leads to the bis(borane) adduct of the corresponding mixed tertiary/secondary phosphine (6), with BH3 acting as both a reducing agent and a Lewis acid. The new compounds were fully characterized, including X-ray diffraction. The ligand properties of 1 and related bonding issues are discussed with help of DFT computations.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4DT00408F
Abstract: A series of eight 5-(TeAr)-6-(SePh)acenaphthenes (Ar = aryl) were prepared and structurally characterised by X-ray crystallography, solution and solid-state NMR spectroscopy and DFT/B3LYP calculations.
Publisher: MDPI AG
Date: 22-04-2017
Publisher: Wiley
Date: 28-06-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5DT00159E
Abstract: Reactions of the dianions [ t BuN(E)P(μ-N t Bu)] 2 2− (E = Se,S) with M( i ) reagents (M = Ag, Au) or HgCl 2 produce complexes of [ t Bu(H)N(E)P(μ-N t Bu) 2 P(E)N t Bu] − with spirocyclic, macrocyclic or ladder structures.
Publisher: Informa UK Limited
Date: 25-01-2021
Publisher: Wiley
Date: 23-07-2020
Publisher: American Chemical Society (ACS)
Date: 18-04-2014
DOI: 10.1021/JA502625Z
Abstract: A proximate Lewis basic group facilitates the mild dehydrogenative P-As intramolecular coupling in the phosphine-arsine peri-substituted acenaphthene 3, affording thermally and hydrolytically stable arsanylidine-phosphorane 4 with a sterically accessible two-coordinate arsenic atom. The formation of 4 is thermoneutral due to the dehydrogenation being concerted with the donor coordination. Reaction of 4 with a limited amount of oxygen reveals arsinidene-like reactivity via formation of cyclooligoarsines, supporting the formulation of the bonding in 4 as base-stabilized arsinidene R3P→AsR.
Publisher: American Chemical Society (ACS)
Date: 25-09-2023
Publisher: American Chemical Society (ACS)
Date: 09-11-2007
DOI: 10.1021/JA076570H
Abstract: We report the design, synthesis, characterization, and operation of a [2]rotaxane in which a palladium-complexed macrocycle can be translocated between 4-dimethylaminopyridine and pyridine monodentate ligand sites via reversible protonation, the metal remaining coordinated to the macrocycle throughout. The substitution pattern of the ligands and the kinetic stability of the Pd-N bond means that changing the chemical state of the thread does not automatically cause a change in the macrocycle's position in the absence of an additional input (heat and/or coordinating solvent/anion). Accordingly, under ambient conditions any of the four sets of protonated and neutral, stable, and metastable co-conformers of the [2]rotaxane can be selected, manipulated, isolated, and characterized.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Alexandra Slawin.