ORCID Profile
0000-0002-7407-8287
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University of St Andrews
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Publisher: Wiley
Date: 05-04-2017
Abstract: The synthesis of a class of electron-rich amino-functionalized β-diketiminato (N-nacnac) ligands is reported, with two synthetic methodologies having been developed for systems bearing backbone NMe
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3DT52140K
Abstract: The reactivity of a soluble phosphinoamide stabilized lithium hydride complex towards some unsaturated organic substrates is described and hydrolithiation and phosphinoamide addition products are reported.
Publisher: American Chemical Society (ACS)
Date: 06-01-2012
DOI: 10.1021/JO202500K
Abstract: The N-heterocyclic carbene catalyzed (4 + 2) cycloaddition between α,β-unsaturated acid fluorides and TMS dienol ethers provides cyclohexene fused β-lactone intermediates stable below -20 °C. These can be intercepted reductively or with organolithium reagents to produce diastereomerically pure cyclohexenes (>20:1 dr) with up to four contiguous stereocenters. The mechanism has been investigated using theoretical calculations and by examining secondary kinetic isotope effects. Together these studies implicate the formation of a diastereomerically pure β-lactone intermediate by a stepwise (4 + 2) cycloaddition involving Michael addition, aldol cyclization, and lactonization.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C2CC37442K
Abstract: Reactions of [Pt(PCy(3))(2)] (Cy = cyclohexyl) with group 12 metal dihalides have afforded the novel metal only Lewis pair (MOLP) complexes, [(Cy(3)P)(2)Pt→MX(2)] (M = Zn or Cd, X = Br or I), or the oxidative addition product, trans-[(Cy(3)P)(2)(I)PtHgI]. The zinc complex represents the first MOLP to contain an unsupported Pt→Zn linkage.
Publisher: Royal Society of Chemistry (RSC)
Date: 03-09-2014
DOI: 10.1039/C4CC04984E
Abstract: Theoretical mechanistic calculations (DFT) on the reactivity of [{((Dip)Nacnac)Mg}2] ((Dip)Nacnac = [(DipNCMe)2CH](-), Dip = C6H3(i)Pr2-2,6) towards CO2 were carried out in order to rationalise the experimental formation of a carbonate (major product) and an oxalate (minor product). Despite its apparent similarity to f-element reactivity, the magnesium(I) bimetallic complex yields the carbonate through a concerted type of pathway rather than via a transient oxo-bridged intermediate. The latter is destabilised due to the electrostatic repulsion between the two magnesium centres. The small energy barrier difference between carbonate and oxalate formation (~10 kcal mol(-1)) may allow for the experimentally observed reactivity to be tuned by changing the sterics and/or electronic properties of the magnesium(I) complex.
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: American Chemical Society (ACS)
Date: 09-12-2013
DOI: 10.1021/OM401059X
Publisher: Royal Society of Chemistry (RSC)
Date: 22-08-2014
DOI: 10.1039/C4DT02074J
Abstract: Reactions of the expanded ring N-heterocyclic carbene, 6-Dip (:C{N(Dip)CH2}2CH2, Dip = 2,6-diisopropylphenyl), with group 15 element trichlorides have yielded the monomeric complexes, [(6-Dip)ECl3] (E = P, As or Sb), two ex les of which (E = P and Sb) have been crystallographically characterised. Reduction of [(6-Dip)PCl3] with KC8 yielded the unusual tetraphosphorus dicationic complex, [(6-Dip)2(μ-P4)]Cl2, the X-ray crystal structure of which shows it to be an ion-separate salt. The compound can also be prepared from the direct reaction of excess 6-Dip with PCl3. Treatment of the cyclic amidinium salt, [6-MesH]Br (6-MesH = [HC{N(Mes)CH2}2CH2](+), Mes = mesityl) with KC8, leads to reductive coupling of the heterocycle and formation of the hindered bis(hexahydropyrimidine), (6-MesH)2. An X-ray crystallographic analysis of (6-MesH)2 shows the compound to have a long central C-C bond, while an electrochemical analysis reveals it to undergo an irreversible two-electron oxidation in dichloromethane solutions.
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B507242E
Abstract: The synthesis and characterisation of the monomeric amidinato-indium(I) and thallium(I) complexes, [M(Piso)].PisoH, M = In or Tl, Piso- = [ArNC(Bu(t))NAr]-, Ar = C6H3Pr(i)2-2,6, are reported. These complexes, in which the metal centre is chelated by the amidinate ligand in an N,eta3-arene-fashion, can be considered as isomers of four-membered group 13 metal(I) carbene analogues. Theoretical studies have compared the relative energies of both isomeric forms of a model complex, [In{PhNC(H)NPh}].
Publisher: American Chemical Society (ACS)
Date: 11-11-2008
DOI: 10.1021/OM8008052
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: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CC35228A
Abstract: Reduction of an N-heterocyclic carbene (NHC) adduct of SnCl(2), viz. [(IPr)SnCl(2)] (IPr = :C{N(Dip)C(H)}(2) Dip = 2,6-diisopropylphenyl), with a magnesium(I) dimer, has afforded the first NHC complex of a row 5 element in its diatomic form, [(IPr)Sn=Sn(IPr)] a computational analysis of the complex indicates that it comprises a singlet state, doubly bonded tin(0) fragment, :Sn=Sn:, datively bonded by two NHC ligands.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CC00996K
Abstract: The synthesis and structural characterisation of the first sodium hydride complex stabilised by sterically demanding pyrazolate ligands are presented.
Publisher: Wiley
Date: 15-06-2016
Abstract: A variety of very bulky amido magnesium iodide complexes, LMgI(solvent)0/1 and [LMg(μ-I)(solvent)0/1 ]2 (L=-N(Ar)(SiR3 ) Ar=C6 H2 {C(H)Ph2 }2 R'-2,6,4 R=Me, Pr(i) , Ph, or OBu(t) R'=Pr(i) or Me) have been prepared by three synthetic routes. Structurally characterized ex les of these materials include the first unsolvated amido magnesium halide complexes, such as [LMg(μ-I)]2 (R=Me, R'=Pr(i) ). Reductions of several such complexes with KC8 in the absence of coordinating solvents have afforded the first two-coordinate magnesium(I) dimers, LMg-MgL (R=Me, Pr(i) or Ph R'=Pr(i) , or Me), in low to good yields. Reductions of two of the precursor complexes in the presence of THF have given the related THF adduct complexes, L(THF)Mg-Mg(THF)L (R=Me R'=Pr(i) ) and LMg-Mg(THF)L (R=Pr(i) R'=Me) in trace yields. The X-ray crystal structures of all magnesium(I) complexes were obtained. DFT calculations on the unsolvated ex les reveal their Mg-Mg bonds to be covalent and of high s-character, while Ph⋅⋅⋅Mg bonding interactions in the compounds were found to be weak at best.
Publisher: Wiley
Date: 13-01-2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3SC52242C
Publisher: Elsevier BV
Date: 10-2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B924367D
Abstract: The preparation of a series of homoleptic, four-coordinate lanthanide(ii) complexes, [Ln(Priso)(2)] (Ln = Sm, Eu or Yb) incorporating the bulky guanidinate ligand Priso(-) ([(ArN)(2)CNPr(i)(2)](-), Ar = 2,6-diisopropylphenyl) is described. X-ray crystallography shows the complexes to be isostructural and to exhibit coordination geometries midway between tetrahedral and planar. Comparisons between the geometries of the complexes and those of the bulkier systems, [Ln(Giso)(2)] (Giso(-) = [(ArN)(2)CNCy(2)](-), Cy = cyclohexyl) are discussed. Attempts to prepare the less hindered amidinate complexes, [Ln(Piso)(2)] (Piso(-) = [(ArN)(2)CBu(t)](-)), were not successful, but did give rise to the heteroleptic complex, [(kappa(1)-N,eta(6)-Piso)Sm(THF)(mu-I)(2)Sm(kappa(1)-N,eta(6)-Piso)]. Whereas the amidinate ligands in this complex chelate the samarium centre in an kappa(1)-N,eta(6)-Ar-fashion, in the closely related complex, [{(kappa(2)-N,N'-Priso)Yb(THF)(mu-I)}(2)], the ytterbium atoms are kappa(2)-N,N'-chelated by the guanidinate ligand. The facility of the planar four-coordinate complex, [Sm(Giso)(2)], to act as a one-electron reducing agent towards a variety of unsaturated substrates has also been explored. The complex has been shown to selectively reductively couple CS(2), via a C-S bond formation, to give the samarium(iii) dimer, [(Giso)(2)Sm(mu-eta(2)-:eta(2)-S(2)CSCS)Sm(Giso)(2)].
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/CH11193
Abstract: The six-membered N-heterocyclic gallium(I) compound [:Ga(ButNacnac)] (ButNacnac– = [{N(Dip)C(But)}2CH]–, Dip =2,6-diisopropylphenyl) has been synthesized, crystallographically characterized, and its electronic properties analyzed using density functional theory. For purposes of comparison, the isoelectronic cationic germanium(II) complex, [:Ge(ButNacnac)][Al{OC(CF3)3}4], has been prepared and structurally authenticated.
Publisher: The Royal Society of Chemistry
Date: 30-10-2020
DOI: 10.1039/9781788012775-00055
Abstract: This chapter provides an overview of recent advances in the chemistry of molecular magnesium complexes. Details on synthesis, structures, properties and reactivity of several magnesium-containing compound classes are covered that showcase principles, advantages and challenges of stoichiometric magnesium chemistry and build some ties to catalytic approaches. New developments with Turbo-Grignard reagents, Turbo-Hauser bases, magnesate complexes, magnesium(II) hydride complexes, dimagnesium(I) complexes and complexes with magnesium–metal or magnesium–metalloid bonds are described, followed by a brief outlook. The sections will show commonly used organic substituents, stabilising ligand classes and some reaction conditions required for the chemistry with magnesium complexes.
Publisher: Wiley
Date: 19-03-2013
Abstract: Quantum chemical calculations using density functional theory at the BP86/TZ2P level have been carried out to determine the geometries and stabilities of Group 13 adducts [(PMe3)(EH3)] and [(PMe3)2(E2H(n))] (E = B-In n = 4, 2, 0). The optimized geometries exhibit, in most cases, similar features to those of related adducts [(NHC(Me))(EH3)] and [(NHC(Me))2(E2H(n))] with a few exceptions that can be explained by the different donor strengths of the ligands. The calculations show that the carbene ligand L = NHC(Me) (:C(NMeCH)2) is a significantly stronger donor than L = PMe3. The equilibrium geometries of [L(EH3)] possess, in all cases, a pyramidal structure, whereas the complexes [L2(E2H4)] always have an antiperiplanar arrangement of the ligands L. The phosphine ligands in [(PMe3)2(B2H2)], which has Cs symmetry, are in the same plane as the B2H2 moiety, whereas the heavier homologues [(PMe3)2(E2H2)] (E = Al, Ga, In) have Ci symmetry in which the ligands bind side-on to the E2H2 acceptor. This is in contrast to the [(NHC(Me))2(E2H2)] adducts for which the NHC(Me) donor always binds in the same plane as E2H2 except for the indium complex [(NHC(Me))2(In2H2)], which exhibits side-on bonding. The boron complexes [L2(B2)] (L = PMe3 and NHC(Me)) possess a linear arrangement of the LBBL moiety, which has a B≡B triple bond. The heavier homologues [L2(E2)] have antiperiplanar arrangements of the LEEL moieties, except for [(PMe3)2(In2)], which has a twisted structure in which the PInInP torsion angle is 123.0°. The structural features of the complexes [L(EH3)] and [L2(E2H(n))] can be explained in terms of donor-acceptor interactions between the donors L and the acceptors EH3 and E2H(n), which have been analyzed quantitatively by using the energy decomposition analysis (EDA) method. The calculations predict that the hydrogenation reaction of the dimeric magnesium(I) compound L'MgMgL' with the complexes [L(EH3)] is energetically more favorable for L = PMe3 than for NHC(Me).
Publisher: Wiley
Date: 02-03-2007
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B822870A
Abstract: The reaction of the manganese precursors [MnOTf(CO)3{1,2-(PH2)2C6H4}], 5, or [MnOTf(CO)3{1,2-(PH2)2C2H4}], 6, with either the silver complex of 1,3-diallylbenzimidazol-2-ylidiene or the free carbene, resulted in the formation of the new, dimeric phosphino-micro-phosphido manganese species 7 and 8. Complex 7 crystallises in two isomeric forms (cis and trans), depending upon the choice of solvent. The structures of both isomers have been determined by single-crystal X-ray techniques.
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: American Chemical Society (ACS)
Date: 09-09-2014
DOI: 10.1021/IC501638V
Abstract: The highly sterically encumbered chelating β-diketiminate ligand, [HC{C(Me)N(2,6-CHPh2-4-MeC6H2)}2](-), (Ar)L(-), has been used to prepare a series of heteroleptic three-coordinate magnesium complexes. Both the bis(imine) and imine-enamine tautomers of the ligand precursor, (Ar)LH, as well as the diethyl ether adduct of the bromide complex [(Ar)LMgBr(OEt2)], the monomeric methyl complex [(Ar)LMgMe], the THF-solvated and unsolvated n-butylmagnesium complexes [(Ar)LMg(n)Bu(THF)] and [(Ar)LMg(n)Bu], and the 1-hexynyl analogue [(Ar)LMgC≡C(n)Bu] have been crystallographically characterized. Both n-butylmagnesium complexes showed remarkable stability in air, both in the solid state and in solution. Single crystals of the highly sensitive magnesium hydride, [(Ar)LMgH], underwent partial hydrolysis by solid-state water diffusion to the isostructural hydroxide compound [(Ar)LMgOH].
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CC18086C
Abstract: Reductions of the β-diketiminato group 14 metal(II) chloride complexes, [((But)MesNacnac)ECl] ((But)MesNacnac = [(MesNCBu(t))(2)CH](-) Mes = mesityl E = Ge, Sn or Pb), with a magnesium(I) dimer have led to differing outcomes, which include the formation of the first β-diketiminato group 14 metal(I) dimer, [{((But)MesNacnac)Sn}(2)].
Publisher: American Chemical Society (ACS)
Date: 06-05-2011
DOI: 10.1021/IC200682P
Abstract: A synthetic route to the new amidine (DipNH)(DipN)C(C(6)H(4)Bu(t)-4) (ButisoH Dip = C(6)H(3)Pr(i)(2)-2,6) has been developed. Its deprotonation with either LiBu(n) or KN(SiMe(3))(2) yields the amidinate complexes [M(Butiso)] (M = Li or K). Their reactions with group 14 element halides seudohalides afford the heteroleptic group 14 complexes [(Butiso)SiCl(3)], [(Butiso)ECl] (E = Ge or Sn), and [{(Butiso)Pb(μ-O(3)SCF(3))(THF)}(∞)], all of which have been crystallographically characterized. In addition, the synthesis and spectroscopic characterization of the homoleptic complex [Pb(Butiso)(2)] is reported. Reductions of the heteroleptic complexes with a soluble magnesium(I) dimer, [{((Mes)Nacnac)Mg}(2)] ((Mes)Nacnac = [(MesNCMe)(2)CH](-) Mes = mesityl), have given moderate-to-high yields of the group 14 element(I) dimers [{(Butiso)E}(2)] (E = Si, Ge, or Sn), the X-ray crystallographic studies of which reveal trans-bent structures. The corresponding lead(I) complex could not be prepared. Comprehensive spectroscopic and theoretical analyses of [{(Butiso)E}(2)] have allowed their properties to be compared. All complexes possess E-E single bonds and can be considered as intramolecularly base-stabilized ex les of ditetrelynes, REER. Taken as a whole, this study highlights the synthetic utility of soluble and easy to prepare magnesium(I) dimers as valuable alternatives to the harsh, and often insoluble, alkali-metal reducing agents that are currently widely employed in the synthesis of low-oxidation-state organometallic/inorganic complexes.
Publisher: Wiley
Date: 31-10-2011
Abstract: Quantum chemical calculations using density functional theory at the BP86/TZVPP level and ab initio calculations at the SCS-MP2/TZVPP level have been carried out for the group 13 complexes [(NHC)(EX(3))] and [(NHC)(2)(E(2)X(n))] (E=B to In X=H, Cl n=4, 2, 0 NHC=N-heterocyclic carbene). The monodentate Lewis acids EX(3) and the bidentate Lewis acids E(2) X(n) bind N-heterocyclic carbenes rather strongly in donor-acceptor complexes [(NHC)(EX(3))] and [(NHC)(2)(E(2)X(n))]. The equilibrium structures of the bidentate complexes depend on the electronic reference state of E(2)X(n), which may vary for different atoms E and X. All complexes [(NHC)(2)(E(2)X(4))] possess C(s) symmetry in which the NHC ligands bind in a trans conformation to the group 13 atoms E. The complexes [(NHC)(2)(E(2)H(2))] with E=B, Al, Ga have also C(s) symmetry with a trans arrangement of the NHC ligands and a planar CE(H)E(H)C moiety that has a E=E π bond. In contrast, the indium complex [(NHC)(2)(In(2) H(2))] has C(i) symmetry with pyramidal-coordinated In atoms in which the hydrogen atoms are twisted above and below the CInInC plane. The latter C(i) form is calculated for all chloride systems [(NHC)(2)(E(2)Cl(2))], but the boron complex [(NHC)(2)(B(2)Cl(2))] deviates only slightly from C(s) symmetry. The B(2) fragment in the linear coordinated complex [(NHC)(2)(B(2))] has a highly excited (3)(1)Σ(g)(-) reference state, which gives an effective B≡B triple bond with a very short interatomic distance. The heavier homologues [(NHC)(2)(E(2))] (E=Al to In) exhibit a anti-periplanar arrangement of the NHC ligands in which the E(2) fragments have a (1)(1) Δ(g) reference state and an E=E double bond. The calculated energies suggest that the dihydrogen release from the complexes [(NHC)(EH(3))] and [(NHC)(2)(E(2)H(n))] becomes energetically more favourable when atom E becomes heavier. The indium complexes should therefore be the best candidates of the investigated series for hydrogen-storage systems that could potentially deliver dihydrogen at close to ambient temperature. The hydrogenation reaction of the dimeric magnesium(I) compound [LMgMgL] (L=β-diketiminate) with [(NHC)(EH(3))] becomes increasingly exothermic with the trend B<Al<Ga<In.
Publisher: American Chemical Society (ACS)
Date: 29-09-2011
DOI: 10.1021/OM200823X
Publisher: Springer Science and Business Media LLC
Date: 06-08-2018
DOI: 10.1038/S41467-018-05504-X
Abstract: Boron hydride clusters are an extremely erse compound class, which are of enormous importance to many areas of chemistry. Despite this, stable aluminium hydride analogues of these species have remained staunchly elusive to synthetic chemists. Here, we report that reductions of an amidinato-aluminium(III) hydride complex with magnesium(I) dimers lead to unprecedented ex les of stable aluminium(I) hydride complexes, [( Ar Nacnac)Mg] 2 [Al 6 H 6 (Fiso) 2 ] ( Ar Nacnac = [HC(MeCNAr) 2 ] − , Ar = C 6 H 2 Me 3 -2,4,6 Mes C 6 H 3 Et 2 -2,6 Dep or C 6 H 3 Me 2 -2,6 Xyl Fiso = [HC(NDip) 2 ] − , Dip = C 6 H 3 Pr i 2 -2,6), which crystallographic and computational studies show to possess near neutral, octahedral hypercloso -hexaalane, Al 6 H 6 , cluster cores. The electronically delocalised skeletal bonding in these species is compared to that in the classical borane, [B 6 H 6 ] 2− . Thus, the chemistry of classical polyhedral boranes is extended to stable aluminium hydride clusters for the first time.
Publisher: Wiley
Date: 08-06-2016
Abstract: A series of magnesium(II) complexes bearing the sterically demanding phosphinoamide ligand, L(-) =Ph2 PNDip(-) , Dip=2,6-diisopropylphenyl, including heteroleptic magnesium alkyl and hydride complexes are described. The ligand geometry enforces various novel ring and cluster geometries for the heteroleptic compounds. We have studied the stoichiometric reactivity of [(LMgH)4 ] towards unsaturated substrates, and investigated catalytic hydroborations and hydrosilylations of ketones and pyridines. We found that hydroborations of two ketones with pinacolborane using various Mg precatalysts is very rapid at room temperature with very low catalyst loadings, and ketone hydrosilylation using phenylsilane is rapid at 70 °C. Our studies point to an insertion/σ-bond metathesis catalytic cycle of an in situ formed "MgH2 " active species.
Publisher: American Chemical Society (ACS)
Date: 09-07-2015
DOI: 10.1021/JACS.5B06439
Abstract: This study details the formal hydrogenation of two magnesium(I) dimers {(Nacnac)Mg}2 (Nacnac = [{(C6H3R2-2,6)NCMe}2CH](-) R = Pr(i) ((Dip)Nacnac), Et ((Dep)Nacnac)) using 1,3-cyclohexadiene. These reactions afford the magnesium(II) hydride complexes, {(Nacnac)Mg(μ-H)}2. Their reactions with excess CO are sterically controlled and lead cleanly to different C-C coupled products, viz. the ethenediolate complex, ((Dip)Nacnac)Mg{κ(1)-O-[((Dip)Nacnac)Mg(κ(2)-O,O-O2C2H2)]}, and the first cyclopropanetriolate complex of any metal, cis-{((Dep)Nacnac)Mg}3{μ-C3(H3)O3}. Computational studies imply the CO activation processes proceed via very similar mechanisms to those previously reported for related reactions involving f-block metal hydride compounds. This work highlights the potential magnesium compounds hold for use in the "Fischer-Tropsch-like" transformation of CO/H2 mixtures to value added oxygenate products.
Publisher: Wiley
Date: 22-07-2014
Abstract: The synthesis of dimeric magnesium(I) compounds of the general type RMgMgR (R=monoanionic substituent) is still a challenging synthetic task and limited to few ex les with sterically demanding ligands with delocalized CN-frameworks that all have been accessed by Na or K metal reduction of magnesium(II) halide precursors. Here we report on the synthesis of a novel diiminophosphinato magnesium(I) compound that has been synthesized by a facile redox reaction using a known magnesium(I) complex. The synthetic strategy may be applicable to other ligand systems and can help expand the class of low oxidation state magnesium complexes even if reductions with Na or K are unsuccessful. The new dimeric magnesium(I) complex has been structurally characterized and undergoes a C-C coupling reaction with tert-butylisocyanate.
Publisher: Wiley
Date: 23-03-2015
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: Wiley
Date: 30-11-2010
Abstract: Reactions of lithium complexes of the bulky guanidinates [{(Dip)N}(2)CNR(2)](-) (Dip=C(6)H(3)iPr(2)-2,6 R=C(6)H(11) (Giso(-)) or iPr (Priso(-)), with NiBr(2) have afforded the nickel(II) complexes [{Ni(L)(μ-Br)}(2)] (L=Giso(-) or Priso(-)), the latter of which was crystallographically characterized. Reduction of [{Ni(Priso)(μ-Br)}(2)] with elemental potassium in benzene or toluene afforded the diamagnetic species [{Ni(Priso)}(2)(μ-C(6)H(5)R)] (R=H or Me), which were shown, by X-ray crystallographic studies, to possess nonplanar bridging arene ligands that are partially reduced. A similar reduction of [{Ni(Priso)(μ-Br)}(2)] in cyclohexane yielded a mixture of the isomeric complexes [{Ni(μ-κ(1)-N-,η(2)-Dip-Priso)}(2)] and [{Ni(μ-κ(2)-N,N'-Priso)}(2)], both of which were structurally characterized. These complexes were also formed through arene elimination processes if [{Ni(Priso)}(2)(μ-C(6)H(5)R)] (R=H or Me) were dissolved in hexane. In that solvent, diamagnetic [{Ni(μ-κ(1)-N-,η(2)-Dip-Priso)}(2)] was found to slowly convert to paramagnetic [{Ni(μ-κ(2)-N,N'-Priso)}(2)], suggesting that the latter is the thermodynamic isomer. Computational analysis of a model of [{Ni(μ-κ(2)-N,N'-Priso)}(2)] showed it to have a Ni-Ni bond that has a multiconfigurational electronic structure. An analogous copper(I) complex [{Cu(μ-κ(2)-N,N'-Giso)}(2)] was prepared, structurally authenticated, and found, by a theoretical study, to have a negligible Cu···Cu bonding interaction. The reactivity of [{Ni(Priso)}(2)(μ-C(6)H(5)Me)] and [{Ni(μ-κ(2)-N,N'-Priso)}(2)] towards a range of small molecules was examined and this gave rise to diamagnetic complexes [{Ni(Priso)(μ-CO)}(2)] and [{Ni(Priso)(μ-N(3))}(2)]. Taken as a whole, this study highlights similarities between bulky guanidinate ligands and the β-diketiminate ligand class, but shows the former to have greater coordinative flexibility.
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B718537E
Publisher: Wiley
Date: 02-12-2016
Abstract: We have synthesized and characterized the monomeric diiminophosphinate-stabilized Group 13 metal(I) complexes [
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: 12-11-2014
Abstract: The tris(pyrazolyl)methane compound HC(3-Ad-5-Mepz)3 [1, 3-Ad-5-Mepz=3-(1-adamantyl)-5-methylpyrazolyl] and its regioisomer, HC(3-Ad-5-Mepz)2 (3-Me-5-Adpz), were synthesized and crystallographically characterized. Deprotonation of 1 with MeLi afforded the lithium complex [{κ(3) -N-C(3-Ad-5-Mepz)3 }Li(thf)], which incorporates a tris(pyrazolyl)methanide ligand of unprecedented bulk. Reaction of 1 with MeMgI gave the ionic coordination complex [{κ(3) -N-HC(3-Ad-5-Mepz)3 }MgMe]I, which was readily deprotonated to afford the neutral compound [{κ(3) -N-C(3-Ad-5-Mepz)3 }MgMe]. The related magnesium butyl compound [{κ(3) -N-C(3-Ad-5-Mepz)3 }MgBu] was prepared from the reaction of 1 and MgBu2 . Treating this with LiAlH4 or LiAlD4 led to rare ex les of terminal magnesium hydride/deuteride complexes, [{κ(3) -N-C(3-Ad-5-Mepz)3 }MgH/D]. All neutral magnesium alkyl and hydride compounds were crystallographically authenticated. Reaction of [{κ(3) κN-C(3-Ad-5-Mepz)3 }Li(thf)] with [YbI2 (thf)2 ] yielded the first structurally characterized f-block tris(pyrazolyl)methanide complex, [{κ(3) -N-C(3-Ad-5-Mepz)3 }YbI(thf)].
Publisher: Wiley
Date: 11-07-2012
Abstract: The reactivity of two β-diketiminate coordinated magnesium(I) dimers, [LMgMgL], L=[(RNCMe)(2) CH](-) , R=C(6) H(3) iPr(2) -2,6 ((Dip) Nacnac(-) ) or mesityl ((Mes) Nacnac(-) ), towards a series of isonitriles and nitriles have been examined. Reactions with the isonitriles, RN≡C: (R=tBu or C(6) H(3) Me(2) -2,6 (Xyl)), led to reductive C-C couplings and the formation of [{((Dip) Nacnac)Mg}(2) {μ-(XylN=C-)(2) }] and [{((Mes) Nacnac)Mg}(2) {μ-(tBuN=C-)(2) }], or a reductive N-C cleavage and the generation of the magnesium cyanide complex, [{((Dip) Nacnac)Mg(μ-CN)}(3) ]. Reactions of the magnesium dimers with benzonitrile, PhC≡N, afforded the C-C-coupled products, [((Dip) Nacnac)Mg[μ-{N=C(Ph)-}(2) ]Mg(NCPh)((Dip) Nacnac)], and [{{((Mes) Nacnac)Mg}(2) [μ-{N=C(Ph)-}(2) ]}(2) ], whereas the reductive CC cleavage of tBuC≡N gave rise to a mixture of [((Dip) Nacnac)Mg(tBu)(NCtBu)] and [{((Dip) Nacnac)Mg(μ-CN)}(3) ]. In contrast, a combination of net nitrile isomerization and C-C coupling processes was involved in the reduction of Me(3) SiC≡N, which yielded [{((Dip) Nacnac)Mg}(2) {μ-(Me(3) SiN=C-)(2) }]. All new compounds were crystallographically and spectroscopically characterized. The outcomes of the reported reactions were found to be dependent upon both the steric bulk of the magnesium(I) reagent, and the nature of the isonitrile/nitrile substituent. This combined with a high degree of selectivity for the reactions, indicates that magnesium(I) dimers may find use by organic and organometallic chemists as viable alternatives to currently available reducing agents that are utilized for the reduction of unsaturated organic substrates.
Publisher: Walter de Gruyter GmbH
Date: 16-07-2019
Abstract: Thermal rearrangement of the 1,2-bis(silylene), [{(4-Bu t Ph)C(NDip) 2 }Si−] 2 (Dip = 2,6-diisopropylphenyl, leads to the silyl-silylene, {(4-Bu t Ph)C(NDip) 2 }Si−Si(H) {N(Dip)C(=NDip)(4-Bu t Ph -H )}, via an intramolecular C−H activation reaction. The X-ray crystal structure, and limited spectroscopic data, for the compound are reported. The structure of the silyl-silylene incorporates an exocyclic imine fragment, which is unprecedented for this compound class.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2DT30299C
Abstract: A high yield synthesis of a new, extremely bulky anionic gallium(I) N-heterocyclic carbene analogue, [(DAB*)Ga:](-) (DAB* = {N(Ar*)C(H)}(2), Ar* = C(6)H(2){C(H)Ph(2)}(2)Me-2,6,4) has been developed and four monomeric sodium complexes of the heterocycle have been crystallographically characterised. The gallium(I) heterocycle has been utilised in the preparations of the heteroleptic zinc and cadmium gallyl complexes, [(DAB*)GaMX(tmeda)] (M = Zn or Cd, X = Br or I), which were crystallographically characterised. In addition, [(DAB*)Ga:](-) was oxidatively coupled to give the diamagnetic digallane(4), [(DAB*)GaGa(DAB*)]. The moderate yield synthesis of the six-membered gallium(I) heterocycle, [((But)MesNacnac)Ga:] ((But)MesNacnac = [(MesNCBu(t))(2)CH](-), Mes = mesityl), is described, and the compound found to be a monomer in the solid state by an X-ray crystallographic analysis. A low yield by-product from this synthesis, [Ga(5)I(4)((But)MesNacnac)(3)], was also isolated and shown by X-ray crystallography to be a rare ex le of a compound bearing a group 13 metal-metal bonded chain stabilised by β-diketiminate ligands. A preliminary analysis of the bonding in the compound was carried out using DFT calculations.
Publisher: American Chemical Society (ACS)
Date: 08-12-2017
DOI: 10.1021/JACS.7B11368
Abstract: The insertion of 1,1-diphenylethylene into the Mg-Mg bond of two magnesium(I) dimers, [(
Publisher: American Chemical Society (ACS)
Date: 15-06-2011
DOI: 10.1021/JA204344E
Abstract: Stoichiometric reduction of the bulky β-diketiminato germanium(II) chloride complex [((But)Nacnac)GeCl] ((But)Nacnac = [{N(Dip)C(Bu(t))}(2)CH](-), Dip = C(6)H(3)Pr(i)(2)-2,6) with either sodium naphthalenide or the magnesium(I) dimer [{((Mes)Nacnac)Mg}(2)] ((Mes)Nacnac = [(MesNCMe)(2)CH](-), Mes = mesityl) afforded the radical complex [((But)Nacnac)Ge:](•) in moderate yields. X-ray crystallographic, EPR/ENDOR spectroscopic, computational, and reactivity studies revealed this to be the first authenticated monomeric, neutral germanium(I) radical.
Publisher: Wiley
Date: 27-07-2018
Publisher: Wiley
Date: 10-2014
Publisher: Wiley
Date: 04-09-2015
Abstract: The reaction of guanidines, triazenes, amidines, and lithium amidinates with trimethylamine alane ([AlH 3 (NMe 3 )]), lithium tetrahydridoaluminate, trimethylaluminum, aluminum trichloride, and indium trichloride is reported. Equimolar reactions utilising hindered N , N ′‐bis(2, 6‐diisopropylphenyl)guanidines afford [{Al X 2 L} n ] species through hydrogen elimination ( X = H) from [AlH 3 (NMe 3 )] ( n = 2) with HCGiso ( 1 ), HDGiso ( 2 ), or HDPiso ( 3 ) [CGiso = N , N ′‐bis(2, 6‐disopropylphenyl)‐ N ′′‐dicyclohexylguanidinate, DGiso = N , N ′, N ′′‐tris(2, 6‐diisopropylphenyl)guanidinate, DPiso = N , N ′‐bis(2, 6‐diisopropylphenyl)‐ P ‐2, 6‐diisopropylphenylphosphguanidinate], or through methane elimination ( X = Me) from AlMe 3 [ n = 1, L = CGiso ( 5 )]. The analogous reactions of the triazene HTiso with LiAlH 4 and AlMe 3 selectively afford [AlH(Tiso) 2 ] ( 4 ) and [AlMe 2 (Tiso)] ( 6 ), respectively [Tiso = 1, 3‐bis(2, 6‐diisopropylphenyl)triazenide]. Reactions of N , N ′‐bis(aryl)formamidines/ates with half an equivalent of AlMe 3 /AlCl 3 result in [Al X L 2 ] complexes [ X = Me L = Fxy ( 7 ) or Fet ( 8 ) X = Cl L = Fet ( 9 ) or L = Fiso ( 10 )] [Fxy = N , N ′‐bis(2, 6‐dimethylphenyl)formamidinate, Fet = N , N ′‐bis(2, 6‐diethylphenyl)formamidinate, Fiso = N , N ′‐bis(2, 6‐diisopropylphenyl)formamidinate]. Treatment of 1 with one equivalent of I 2 yields [AlI 2 (CGiso)] ( 11 ). Attempts to prepare [InCl 2 L] congeners of 11 with L = Fxy and Fet led to the isolation of prodigious quantities of [InCl 3 (HFxy) 2 ] ( 12 ) and [InCl 2 (Fet)(HFet)] ( 13 ) due to adventitious water. The X‐ray crystal structures of 1 – 13 are reported.
Publisher: Wiley
Date: 11-12-2014
Publisher: Wiley
Date: 05-10-2012
Abstract: The new sterically demanding aminoiminophosphorane Ph(2)P(=NDip)(NHDip) (Dip = C(6)H(3)-2,6-iPr(2) LH, 1) has been prepared as a precursor to the potassium complex [LK] (2) and a series of heteroleptic zinc(II) complexes, namely [(LZnBr)(2)] (3), [LZnMe] (4), [LZnEt] (5), and [(LZnI)(2)] (6). The products have been obtained either through a salt metathesis route by using complex 2 and ZnBr(2) to give compound 3, through a direct reaction of ligand precursor 1 and ZnR(2) (R = Me or Et) yielding complexes 4 or 5, respectively, or through iodination of complexes 4 or 5 by using I(2) to afford compound 6. Reduction of the heteroleptic zinc(II) halide complexes 3 or 6 by using a dimeric magnesium(I) compound as a selective, stoichiometric, and soluble reducing agent afforded the new zinc(I) dimer [(LZn)(2)] (7) in good yield. Compounds 1-7 were crystallographically and spectroscopically characterized and the coordination behavior of the diiminophosphinate ligand has been investigated and compared with related CN-based ligands. An initial reactivity study has been carried out on [(LZn)(2)] (7) by using small-scale reactions and the oxidative addition of small alkyl halides across the Zn-Zn bond has been found to generate equimolar amounts of the alkyl complexes 4 or 5 and the halide complexes 3 or 6, respectively.
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/CH13229
Abstract: The reaction of the sterically demanding bis(iminophosphorane)methane, {DipN=P(Ph2)}2CH2, H2L 1 (where Dip = 2,6-iPr2C6H3), with one or two equivalents of AlMe3 in toluene under varying conditions led to the methanide complex [HLAlMe2] 4, and the methandiide complex [L(AlMe2)2] 5, respectively. Iterative iodination of complex 5 with I2 in toluene yielded the complexes [L(AlMeI)2] 6 and [L(AlI2)2] 7. The complexes 4–7 were structurally characterised. The methanide 4 forms a puckered six-membered ring without Al-C(methanide) contact and the complexes 5 and 6 show coordination of the methandiide ligand to two Al atoms forming two four-membered rings on the central spirocyclic carbon centre. Complex 7 shows an asymmetric coordination mode of the two Al centres to the methandiide ligand in the solid state with an almost planar, severely distorted three-coordinate methandiide carbon atom and only one short Al–C bond.
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: 2010
DOI: 10.1039/B922002J
Abstract: The reductions of benzophenone and anthracene with dimeric magnesium(I) complexes lead to thermally stable magnesium ketyl and magnesium anthracene complexes, respectively both have been structurally characterised.
Publisher: Wiley
Date: 06-07-2005
Abstract: The reactivity of two sterically bulky amidines, ArNC(R)N(H)Ar (Ar=2,6-diisopropylphenyl R=H (HFiso) tBu, (HPiso)) towards LiMH4, M=Al or Ga, [AlH3(NMe3)], and [GaH3(quin)] (quin=quinuclidine) has been examined. This has given rise to a variety of very thermally stable aluminum and gallium hydride complexes. The structural motif adopted by the prepared complexes has been found to be dependent upon both the amidinate ligand and the metal involved. The 1:1 reaction of HFiso with LiAlH4 yielded dimeric [{AlH3(mu-Fiso)Li(OEt2)}2]. Amidine HFiso reacts in a 1:1 ratio with [AlH3(NMe3)] to give the unusual hydride-bridging dimeric complex, [{AlH2(Fiso)}2], in which the Fiso- ligand is nonchelating. The equivalent reaction with the bulkier amidine, HPiso, yielded a related hydride-bridging complex, [{AlH2(Piso)}2], in which the Piso- ligand is chelating. In contrast, the treatment of [GaH3(quin)] with one equivalent of HFiso afforded the four-coordinate complex [GaH2(quin)(Fiso)], in which the Fiso- ligand acts as a localized monodentate amido-imine ligand. The 2:1 reactions of HFiso with [AlH3(NMe3)] or [GaH3(quin)] gave the monomeric complexes [MH(Fiso)2], which are thermally robust and which exhibit chelating amidinate ligands. In contrast, HPiso did not give 2:1 complexes in its reactions with either of the Group 13 trihydride precursors. For sake of comparison, the reactions of [AlH3(NMe3)] and [GaH3(quin)] with the bulky carbodiimide ArN=C=NAr and the thiourea Ar(H)NC(=S)N(H)Ar were examined. These last reactions afforded the five-coordinate thioureido complexes, [MH{N(Ar)C[N(H)(Ar)]S}2], M=Al or Ga.
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/CH15206
Abstract: The first ex les of well-defined alkali metal hydride complexes have been synthesised and characterised in recent years, and their properties and underlying principles for their generation and stabilisation are emerging. This article gives an account of the hydrides of the alkali metals (Group 1 metals) and selected ‘-ate’ complexes containing hydrides and alkali metals, and reviews the chemistry of well-defined alkali metal hydride complexes including their syntheses, structures, and characteristics. The properties of the alkali metal hydrides LiH, NaH, KH, RbH, and CsH are dominated by their ionic NaCl structure. Stable, soluble, and well-defined LiH and NaH complexes have been obtained by metathesis and β-hydride elimination reactions that require suitable ligands with some steric bulk and the ability to coordinate to several metal ions. These novel hydride complexes reward with higher reactivity and different properties compared with their parent ionic solids.
Publisher: Wiley
Date: 09-07-2012
Publisher: American Chemical Society (ACS)
Date: 15-12-2010
DOI: 10.1021/JP109547W
Abstract: High-resolution X-ray diffraction data, coupled with theoretical calculations, are used to demonstrate the presence of a non-nuclear local maximum in the electron density of a dimeric Mg(I) molecule. This is the first time such a non-nuclear attractor (NNA) has been observed in a stable molecular species. Multipole modeling of the Mg(I) centers requires use of expansion/contraction (κ) coefficients taken from density functional theory (DFT), since accurate scattering factors for Mg(I) are not available. The model developed accurately accounts for the electron density in the Mg-Mg region and is in excellent agreement with directly calculated DFT data. Within the quantum theory of atoms in molecules (QTAIM), this molecule is not bound by a Mg-Mg bond but rather by two Mg-"pseudo-atom" bonds. The NNA is associated with a large region of negative Laplacian in the Mg-Mg internuclear region and arises from the overlap of 3s orbitals in this long, nonpolar "bond". The pseudoatomic basin associated with the NNA contains 0.8 electrons, which are highly delocalized and hence weakly bound. Possible implications of this unusual electronic structure for the chemistry of such molecules, including their use as excellent reducing agents, are discussed.
Publisher: CSIRO Publishing
Date: 18-02-2022
DOI: 10.1071/CH21283
Abstract: The potassium salt of an extremely bulky β-diketiminate, [K(Ar*Nacnac)] (Ar*Nacnac, [(Ar*NCMe)2CH]− Ar*, C6H2Me{C(H)Ph2}2-4,2,6) was reacted with either CaI2 or YbI2(THF)2, which afforded [(Ar*Nacnac)MI] (M = Ca or Yb). These are the first ex les of structurally characterised, donor solvent-free, N-arene substituted β-diketiminato calcium and ytterbium complexes that incorporate a terminal iodide ligand. Reduction of [(Ar*Nacnac)CaI] with sodium metal gave a complex product mixture, from which a few crystals of the β-diketiminate C–H activated product, [{Ca(μ-Ar*Nacnac-H)}2], were obtained and crystallographically characterised. In an attempt to form a terminal ytterbium hydride compound, treatment of [(Ar*Nacnac)YbI] with K[HBEt3] gave a good yield of the contact ion pair compound [(Ar*Nacnac)Yb(HBEt3)].
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3CC01609A
Abstract: Go-Al! low valent aluminium scores a Hat-trick by converting C 60 to a tri-substituted molecular aluminium fulleride.
Publisher: Springer Science and Business Media LLC
Date: 08-2010
DOI: 10.1038/NCHEM.762
Abstract: The desorption of dihydrogen from magnesium(II) hydride, MgH2 (containing 7.6 wt% H), is reversible. MgH2 therefore holds promise as a hydrogen storage material in devices powered by fuel cells. We believed that dimeric magnesium(I) dimers (LMgMgL, L=β-diketiminate) could find use as soluble models to aid the study of the mechanisms and/or kinetics of the hydrogenation of magnesium and its alloys. Here, we show that LMgMgL can be readily hydrogenated to yield LMg(µ-H)2MgL by treatment with aluminium(III) hydride complexes. In one case, hydrogenation was reversed by treating LMg(µ-H)2MgL with potassium metal. The hydrogenation by-products are the first thermally stable, neutral aluminium(II) hydride complexes to be produced, one of which, [{(IPr)(H)2Al}2] (IPr=:C[{(C6H3-i-Pr(2)-2,6)NCH}2]), is an N-heterocyclic carbene adduct of the elusive parent dialane4 (Al2H4). A computational analysis of this compound is presented.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4DT01185F
Abstract: Sequential lithiation of a sterically demanding bis(iminophosphoranyl)methane afforded di- and trianionic methandiide lithium complexes and their structures and coordination behaviour have been studied with solid state and solution methods.
Publisher: Wiley
Date: 18-01-2011
DOI: 10.1002/MRC.2721
Abstract: In this paper, the paramagnetic properties of a novel magnesium ketyl radical (compound 1), formed by reduction of benzophenone with a dimeric Mg(I) complex in the presence of dimethylaminopyridine, are described. Using CW EPR, ENDOR and special TRIPLE resonance, the spin distribution in the radical has been explored at variable temperatures (200-298 K). At 298 K, most of the unpaired spin is found to be confined to the (OCPh(2)(•)) fragment based on the hyperfine couplings (hfc's) of o-H = 8.30, m-H = 3.00 and p-H = 9.95 MHz. Smaller hfc's to (25)Mg (5.54 MHz) and (14)N(DMAP) (0.90 MHz) were also evidenced in the 298 K EPR spectrum, indicating some spin delocalisation onto the Mg(Nacnac)(DMAP) fragment. At lower temperatures, restricted rotations of the diphenyl rings create an inequivalent spin distribution in the two rings, with o(1)-H = 8.80, o(2)-H = 7.85, m-H = 3.00 and p-H = 10.00 MHz.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3DT50505G
Abstract: Uncatalysed 1,3-dipolar cycloaddition reactions between two phosphaalkynes, P≡CR (R = Bu(t) or Me), and a series of di-, tri- and poly-azido precursor compounds have given very high yields of a range of triazaphosphole substituted systems. These comprise the 1,1'-bis(triazaphosphole)ferrocenes, [Fe{C5H4(N3PCR)}2], the tris(triazaphosphole)cyclohexane, cis-1,3,5-C6H9(N3PCBu(t))3, and the poly(allyltriazaphosphole)s, {C3H5(N3PCR)}∞. Electrochemical studies on the 1,1'-bis(triazaphosphole)ferrocenes reveal the compounds to undergo reversible 1-electron oxidation processes, at significantly more positive potentials than ferrocene itself. Attempts to chemically oxidise one 1,1'-bis(triazaphosphole)ferrocene with a silver salt, Ag[Al{OC(CF3)3}4] were not successful, and led to the formation of a silver coordination complex, [{Fe[μ-C5H4(N3PCBu(t))]2(μ-Ag)}2][Al{OC(CF3)3}4]2, thereby demonstrating the potential the reported triazaphosphole substituted systems possess as novel ligands in coordination chemistry.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0DT01831G
Abstract: The chemistry of the s-block metals is dominated by the +1 oxidation state for the Alkali metals (group 1) and the +2 oxidation state for the Alkaline Earth metals (group 2). In recent years, a series of stable dimeric magnesium(I) compounds has been prepared and their chemistry has started to develop. These complexes feature "deformable" Mg-Mg single bonds and are stabilised by sterically demanding and chelating anionic N-ligands that prevent their disproportionation. They have rapidly proven useful in organic and organometallic/inorganic reduction reactions as hydrocarbon soluble, stoichiometric, selective and safe reducing agents. The scope of this perspective focuses on stable molecular compounds of the general type LMgMgL and describes their synthesis, structures, theoretical and spectroscopic studies as well as their further chemistry. Also, comparisons are drawn with related complexes including magnesium(II) hydrides and dimeric zinc(I) compounds.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C002940H
Abstract: High yielding "click" reactions between phosphaalkynes and organo-triazides have afforded ex les of tris(triazaphosphole)s, the utility of which as a new class of tripodal P(3)-ligand has been demonstrated with the preparation of an unusual diplatinum complex.
Publisher: Elsevier BV
Date: 04-2011
Publisher: Springer Science and Business Media LLC
Date: 20-05-2011
Publisher: MDPI AG
Date: 19-04-2017
DOI: 10.20944/PREPRINTS201704.0125.V1
Abstract: Substituted bis(iminophosphoranyl)methanes are CH acidic compounds that can form complexes with formally dianionic central carbon centres. The reaction of H2C(Ph2P=NDip)2 (& equiv H2L), Dip = 2,6-diisopropylphenyl, with one equivalent of di-n-butylmagnesium afforded the methanide complex [HLMgnBu] 1. Treatment of complex 1 with phenylsilane in aromatic solvents at elevated temperatures afforded the methanediide complex [(LMg)2] 2 presumably via the MgH intermediate [(HLMgH)n] (n = 1 or 2). The reaction of 1 with LiAlH4 in diethyl ether yielded the AlH complex [HLAlH2] 3. Alternatively, this complex was also obtained from the reaction of H2L with AlH3∙NMe3. The molecular structures of [HLMgnBu] 1, [(LMg)2] 2, and [HLAlH2] 3 are reported. Complex 3 shows no sign of H2 elimination to a methanediide species at elevated temperatures in contrast to the facile elimination of the putative reaction intermediate [(HLMgH)n] (n = 1 or 2) to form [(LMg)2] 2. The chemical properties of complex 2 were investigated and this complex appears to be stable against coordination with strong donor molecules.
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: Springer Science and Business Media LLC
Date: 26-01-2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0DT00589D
Abstract: The preparation of a series of amidinato and guanidinato zinc halide complexes incorporating ligands of varying steric bulk is described, and their thermal stabilities compared. Salt elimination reactions between [M(Giso)] (M = K or Li Giso = [(ArN)(2)CNCy(2)](-), Ar = 2,6-diisopropylphenyl, Cy = cyclohexyl) and ZnX(2) (X = I or Br) have yielded the monomeric complexes [(Giso)ZnI] and [(Giso)Zn(mu-Br)(2)Li(OEt(2))(2)]. Both have been crystallographically characterised and the former shown to slowly decompose in solution at ambient temperature to give the carbodiimide, ArN[double bond, length as m-dash]C[double bond, length as m-dash]NAr. In contrast, reactions between alkali metal complexes of a less bulky guanidinate, [M(Priso)] (Priso = [(ArN)(2)CNPr(i)(2)](-)) and ZnX(2) have yielded [(IZn)(2)(mu-NPr(i)(2)){mu-N,N'-(NAr)(2)CH}] and [(Priso)Zn(mu-Br)(2)Li(OEt(2))(2)]. The latter decomposes in solution at ambient temperature, generating ArN[double bond, length as m-dash]C[double bond, length as m-dash]NAr, which was also produced in the preparation of the former. Analogies are drawn between the decomposition of [(Priso)Zn(mu-Br)(2)Li(OEt(2))(2)] and the carbonic anhydrase catalysed dehydration of bicarbonate. Two bulky amidinato zinc complexes, [{(Piso)Zn(mu-Br)}(2)] and [Zn(Piso)(2)] (Piso = [(ArN)(2)CBu(t)](-)) have been prepared, structurally characterised and shown to be markedly more thermally stable than the zinc guanidinate compounds. Attempts to reduce several of the zinc(ii) halide complexes to dimeric zinc(i) compounds were so far unsuccessful, in all cases leading to the deposition of zinc metal.
Publisher: American Chemical Society (ACS)
Date: 09-12-2008
DOI: 10.1021/JA807333F
Abstract: The synthesis of N-heterocyclic carbene-diphosphine macrocycles by metal template assisted cyclization reactions has been explored. Attempts to prepare the facial tungsten tricarbonyl precursor complex containing an NH,NH-functionalized carbene and a suitable diphosphine resulted in displacement of the coordinated carbene and the isolation of the corresponding diphosphine tungsten tetracarbonyl [3]. The Re(I) chloro tetracarbonyl complex bearing an NH,NH-functionalized carbene ligand [5] can be prepared and is a suitable precursor for the subsequent formation of the carbene-diphosphine tricarbonyl intermediate [H(2)-6]Cl bearing reactive 2-fluoro substituents at the phosphine-phenyl groups. Two of these fluoro substituents are displaced by a nucleophilic attack upon deprotonation of the coordinated NH,NH-functionalized carbene resulting in new C-N bonds resulting in the partially coupled intermediate, [10], followed by the desired complex with the macrocyclic ligand [8]Cl. Compounds [H-7]Cl and [8]Cl are also formed during the synthesis of [H(2)-6]Cl as a result of spontaneous HF elimination. Complex [8](+) may be converted to the neutral dicarbonyl chloro analog [11] by action of Me(3)NO. Related chemistry with analogous manganese complexes is observed. Thus, from the NH,NH-functionalized carbene manganese bromo tetracarbonyl [12], the diphosphine manganese carbene tricarbonyl cation [H(2)-13] may be readily prepared which provides the macrocyclic carbene-diphosphine tricarbonyl cation [14](+) following base promoted nucleophilic intramolecular displacement of fluoride. Again, [14](+) is converted to the neutral bromo dicarbonyl upon reaction with Me(3)NO. All complexes with the exception of the reaction intermediate [10] have been characterized by spectroscopic and analytical methods in addition to X-ray crystallographic structure determinations for complexes [3], [5], [H(2)-6]Cl, [H(2)-6][9], [8]Cl, [10], [11], [12], and [14]Br.
Publisher: American Chemical Society (ACS)
Date: 11-03-2009
DOI: 10.1021/JA900385U
Abstract: Experimental charge density modeling of a magnesium dimer complex and subsequent topological analysis reveals the existence of a chemical bond between the two central Mg atoms. Analysis of the molecular system using the energy density, the source function, and several density profiles along the entire bond path portrays the bond as one between two monovalent Mg atoms containing significant covalent character.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5SC01561H
Abstract: Amine bases are shown to induce reductive elimination of dihydrogen from terphenyltin trihydride.
Publisher: Elsevier BV
Date: 2008
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7DT04048B
Abstract: Monomeric group 13 metal( i ) complexes of gallium, indium and thallium stabilised by a sterically demanding bis(iminophosphoranyl)methanide ligand have been prepared and characterised.
Publisher: Wiley
Date: 09-12-2016
Abstract: The first ex le of a well-defined binary, low-oxidation-state aluminum hydride species that is stable at ambient temperature, namely the dianion in [{(
Publisher: American Chemical Society (ACS)
Date: 07-04-2010
DOI: 10.1021/OM1001606
Publisher: Canadian Science Publishing
Date: 06-2018
Abstract: Three extremely bulky 1,3,5-triazapentadienes, Ar NNNH ( Ar NNN = N{C(Bu t )=N(Ar)} 2 Ar = Mes (mesityl), Dep (2,6-diethylphenyl), or Dip (2,6-diisopropylphenyl)) have been prepared and structurally characterized. These are readily deprotonated, yielding a series of lithium and potassium triazapentadienyl complexes, one of which, ( Dip NNN)Li, has been structurally characterized. Similarly, three monomeric triazapentadienyl magnesium iodide complexes, ( Ar NNN)MgI(OEt 2 ), and a dimeric calcium counterpart, {( Mes NNN)Ca(THF)(μ-I)} 2 , have been prepared. Attempts to reduce the former gave homoleptic bis(triazapentadienyl) magnesium complexes, ( Ar NNN) 2 Mg (Ar = Mes or Dep) as the main products. One reaction also gave a very low yield of the magnesium(I) dimer, {( Dep NNN)Mg–} 2 , which was structurally characterized. In related chemistry, two triazapentadienyl boron difluoride compounds, ( Ar NNN)BF 2 (Ar = Mes or Dep), have been synthesized, and unsuccessful attempts have been made to reduce these to boron(I) heterocycles. For sake of comparison, attempts have been made to prepare a series of related amino-substituted β-diketiminato group 13 element(I) heterocycles. Although these were also not successful, several group 13 element(III) halide complexes incorporating this ligand class have been characterized.
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: American Chemical Society (ACS)
Date: 19-07-2010
DOI: 10.1021/OM100595A
Publisher: American Association for the Advancement of Science (AAAS)
Date: 14-12-2007
Abstract: The chemistry of the group 2 metals (beryllium, magnesium, calcium, strontium, and barium) is dominated by the +2 oxidation state. Here, we report the reductions of two magnesium(II) iodide complexes with potassium metal in toluene, leading to thermally stable magnesium(I) compounds, (L)MgMg(L) (where L is [(Ar)NC(NPr i 2 )N(Ar)] – or {[(Ar)NC(Me)] 2 CH} – , Ar is 2,6-diisopropylphenyl, Me is methyl, and Pr i is isopropyl) in moderate yields. The results of x-ray crystallographic and theoretical studies are consistent with central Mg 2+ 2 units that have single, covalent magnesium-magnesium bonding interactions with 2.8508 ± 0.0012 (standard deviation) and 2.8457 ± 0.0008 angstrom bond lengths, respectively, and predominantly ionic interactions with the anionic ligands (L).
Publisher: Wiley
Date: 13-12-2013
Abstract: The assembly of well-defined large cluster compounds of ionic light metal hydrides is a synthetic challenge and of importance for synthesis, catalysis, and hydrogen storage. The synthesis and characterization of a series of neutral and anionic pyrazolate-stabilized lithium hydride clusters with inorganic cores in the nanometer region is now reported. These complexes were prepared in a bottom-up approach using alkyl lithium and lithium pyrazolate mixtures with silanes in hydrocarbon solutions. Structural characterization using synchrotron radiation revealed isolated cubic clusters that contain up to 37 Li(+) cations and 26 H(-) ions. Substituted pyrazolate ligands were found to occupy all corners and some edges for the anionic positions.
Publisher: MDPI AG
Date: 22-04-2017
Publisher: Springer Berlin Heidelberg
Date: 2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B715327A
Abstract: 1-Trimethylsilylphosphirane, C2H4PSiMe3, has been prepared on a multi gram scale from P(SiMe3)3 via CICH2CH2P(SiMe3)2. C2H4PSiMe3 is readily susceptible to protonolysis forming the thermally unstable parent phosphirane, C2H4PH, in good yields. Reaction of C2H4PSiMe3 with fac-M(CO)3(CH3CN)3 (M = Cr, Mo) or [Fe(eta5-C5H5)(eta6-C6H6)](PF6) give rise tofac-M(CO)3(C2H4PSiMe3)3 and [Fe(eta5-C5H5)(C2H4PSiMe3)3](PF6) respectively. Protonolysis of the free or coordinated 1-trimethylsilylphosphirane readily causes P-Si cleavage to give rise to the parent C2H4PH or the respective complexes,fac-M(CO)3(C2H4PH)3 andfac-[Fe(eta5-C5H5)(C2H4PH)3](PF6) in situ. All new complexes are characterised by analytical and spectroscopic methods and the X-ray crystal structures of fac-Cr(CO)3(C2H4PSiMe3)3 and fac-Mo(CO)3(C2H4PH)3 have also been determined.
Publisher: Springer Science and Business Media LLC
Date: 22-05-2010
Publisher: Wiley
Date: 11-09-2015
Abstract: The first ex les of magnesium(I) dimers bearing tripodal ligands, [(Mg{κ(3) -N,N',O-(ArNCMe)2 (OCCPh2 )CH})2 ] [Ar=2,6-iPr2 C6 H3 (Dip) 7, 2,6-Et2 C6 H3 (Dep) 8, or mesityl (Mes) 9] have been prepared by post-synthetic modification of the β-diketiminato ligands of previously reported magnesium(I) systems, using diphenylketene, OCCPh2 . In contrast, related reactions between β-diketiminato magnesium(I) dimers and the isoelectronic ketenimine, MesNCCPh2 , resulted in reductive insertion of the substrate into the MgMg bond of the magnesium(I) reactant, and formation of [{(Nacnac)Mg}2 {μ-κ(2) -N,C-(Mes)NCCPh2 }] (Nacnac=[(ArNCMe)2 CH](-) Ar=Dep 10 or Mes 11). Reactions of the four-coordinate magnesium(I) dimer 8 with excess CO2 are readily controlled, and cleanly give carbonate [(LMg)2 (μ-κ(2) :κ(2) -CO3 )] 12 (L=[κ(3) -N,N',O-(DepNCMe)2 (OCCPh2 )CH](-) thermodynamic product), or oxalate [(LMg)2 (μ-κ(2) :κ(2) -C2 O4 )] 13 (kinetic product), depending on the reaction temperature. Compound 12 and CO are formed by reductive disproportionation of CO2 , whereas 13 results from reductive coupling of two molecules of the gas. Treatment of 8 with an excess of N2 O cleanly gives the μ-oxo complex [(LMg)2 (μ-O)] 14, which reacts facilely with CO2 to give 12. This result presents the possibility that 14 is an intermediate in the formation of 12 from the reaction of 8 and CO2 . In contrast to its reactions with CO2 , 8 reacts with SO2 over a wide temperature range to give only one product the first ex le of a magnesium dithionite complex, [(LMg)2 (μ-κ(2) :κ(2) -S2 O4 )] 16, which is formed by reductive coupling of two molecules of SO2 , and is closely related to f-block metal dithionite complexes derived from similar SO2 reductive coupling processes. On the whole, this study strengthens previously proposed analogies between the reactivities of magnesium(I) systems and low-valent f-block metal complexes, especially with respect to small molecule activations.
Publisher: Wiley
Date: 23-07-2020
Publisher: Elsevier BV
Date: 10-2010
Publisher: Springer Science and Business Media LLC
Date: 24-06-2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1DT10678C
Abstract: The preparation of a series of extremely bulky secondary amines, Ar*N(H)SiR(3) (Ar* = C(6)H(2){C(H)Ph(2)}(2)Me-2,6,4 R(3) = Me(3), MePh(2) or Ph(3)) is described. Their deprotonation with either LiBu(n), NaH or KH yields alkali metal amide complexes, several monomeric ex les of which, [Li(L){N(SiMe(3))(Ar*)}] (L = OEt(2) or THF), [Na(THF)(3){N(SiMe(3))(Ar*)}] and [K(OEt(2)){N(SiPh(3))(Ar*)], have been crystallographically characterised. Reactions of the lithium amides with germanium, tin or lead dichloride have yielded the first structurally characterised two-coordinate, monomeric amido germanium(II) and tin(II) chloride complexes, [{(SiR(3))(Ar*)N}ECl] (E = Ge or Sn R = Me or Ph), and a chloride bridged amido-lead(II) dimer, [{[(SiMe(3))(Ar*)N]Pb(μ-Cl)}(2)]. DFT calculations on [{(SiMe(3))(Ar*)N}GeCl] show its HOMO to exhibit Ge lone pair character and its LUMO to encompass its Ge based p-orbital. A series of bulky amido silicon(IV) chloride complexes have also been prepared and several ex les, [{(SiR(3))(Ar*)N}SiCl(3)] (R(3) = Me(3), MePh(2)) and [{(SiMe(3))(Ar*)N}SiHCl(2)], were crystallographically characterised. The sterically hindered group 14 complexes reported in this study hold significant potential as precursors for kinetically stabilised low oxidation state and/or low coordination number group 14 complexes.
Publisher: Wiley
Date: 14-01-2010
Abstract: The preparation and characterization of a series of magnesium(II) iodide complexes incorporating beta-diketiminate ligands of varying steric bulk and denticity, namely, [(ArNCMe)(2)CH](-) (Ar=phenyl, ((Ph)Nacnac), mesityl ((Mes)Nacnac), or 2,6-diisopropylphenyl (Dipp, (Dipp)Nacnac)), [(DippNCtBu)(2)CH](-) ((tBu)Nacnac), and [(DippNCMe)(Me(2)NCH(2)CH(2)NCMe)CH](-) ((Dmeda)Nacnac) are reported. The complexes [((Ph)Nacnac)MgI(OEt(2))], [((Mes)Nacnac)MgI(OEt(2))], [((Dmeda)Nacnac)MgI(OEt(2))], [((Mes)Nacnac)MgI(thf)], [((Dipp)Nacnac)MgI(thf)], [((tBu)Nacnac)MgI], and [((tBu)Nacnac)MgI(DMAP)] (DMAP=4-dimethylaminopyridine) were shown to be monomeric by X-ray crystallography. In addition, the related beta-diketiminato beryllium and calcium iodide complexes, [((Mes)Nacnac)BeI] and [{((Dipp)Nacnac)CaI(OEt(2))}(2)] were prepared and crystallographically characterized. The reductions of all metal(II) iodide complexes by using various reagents were attempted. In two cases these reactions led to the magnesium(I) dimers, [((Mes)Nacnac)MgMg((Mes)Nacnac)] and [((tBu)Nacnac)MgMg((tBu)Nacnac)]. The reduction of a 1:1 mixture of [((Dipp)Nacnac)MgI(OEt(2))] and [((Mes)Nacnac)MgI(OEt(2))] with potassium gave a low yield of the crystallographically characterized complex [((Dipp)Nacnac)Mg(mu-H)(mu-I)Mg((Mes)Nacnac)]. All attempts to form beryllium(I) or calcium(I) dimers by reductions of [((Mes)Nacnac)BeI], [{((Dipp)Nacnac)CaI(OEt(2))}(2)], or [{((tBu)Nacnac)CaI(thf)}(2)] have so far been unsuccessful. The further reactivity of the magnesium(I) complexes [((Mes)Nacnac)MgMg((Mes)Nacnac)] and [((tBu)Nacnac)MgMg((tBu)Nacnac)] towards a variety of Lewis bases and unsaturated organic substrates was explored. These studies led to the complexes [((Mes)Nacnac)Mg(L)Mg(L)((Mes)Nacnac)] (L=THF or DMAP), [((Mes)Nacnac)Mg(mu-AdN(6)Ad)Mg((Mes)Nacnac)] (Ad=1-adamantyl), [((tBu)Nacnac)Mg(mu-AdN(6)Ad)Mg((tBu)Nacnac)], and [((Mes)Nacnac)Mg(mu-tBu(2)N(2)C(2)O(2))Mg((Mes)Nacnac)] and revealed that, in general, the reactivity of the magnesium(I) dimers is inversely proportional to their steric bulk. The preparation and characterization of [((tBu)Nacnac)Mg(mu-H)(2)Mg((tBu)Nacnac)] has shown the compound to have different structural and physical properties to [((tBu)Nacnac)MgMg((tBu)Nacnac)]. Treatment of the former with DMAP has given [((tBu)Nacnac)Mg(H)(DMAP)], the X-ray crystal structure of which disclosed it to be the first structurally authenticated terminal magnesium hydride complex. Although attempts to prepare [((Mes)Nacnac)Mg(mu-H)(2)Mg((Mes)Nacnac)] were not successful, a neutron diffraction study of the corresponding magnesium(I) complex, [((Mes)Nacnac)MgMg((Mes)Nacnac)] confirmed that the compound is devoid of hydride ligands.
Publisher: Wiley
Date: 30-03-2012
Publisher: American Chemical Society (ACS)
Date: 25-09-2023
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 Andreas Stasch.