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Cameron Jones

Publications and source records attributed to Cameron Jones.

At least 19 recordsLinked to original sources
PubMed2007

Homo- and heteroleptic complexes of four-membered group 13 metal(I) N-heterocyclic carbene analogues with group 10 metal(0) fragments.

A series of complexes between recently developed four-membered group 13 metal(I) heterocycles and group 10 metal(0) fragments have been prepared and structurally characterized. One prepared complex, [Pt{Ga[N(Ar)]2CNCy2}3] (Ar = C6H3Pri2-2,6; Cy = cyclohexyl), possesses the shortest Pt-Ga bonds yet reported, the covalent components of which are suggested by theoretical studies to have significant pi character.

Journal Article↗
PubMed2007

Base-stabilized amidodiarsenes: synthesis, structure, and theoretical studies.

The guanidinato- or amidinato-bridged diarsenes [As2{mu-(ArN)2CR}2] (Ar = C6H3Pri2-2,6; R = N(C6H11)2, NPri2, or But) have been prepared by reduction of the corresponding As(III) precursors, [Cl2As{kappa2-N,N'-(ArN)2CR}]. Theoretical studies suggest that the As-As bonds of the dimers have significant double-bond character, the sigma and pi components of which are derived mainly from As p orbital overlaps.

Journal Article↗
PubMed2006

Synthesis and characterisation of complexes of Group 13 metal amidinate heterocycles with the CpFe(CO)2 fragment.

The first examples of complexes between a 4-membered amidinato-Group 13 metal(III) heterocycle and a transition metal fragment are formed in salt elimination reactions between Na[CpFe(CO)2] and [MX2(amid)], M=Al, Ga or In; X=Cl or Br; amid-=[(RN)2CBut]-; R=Pri or cyclohexyl (Cy). The formed complexes, [CpFe(CO)2M(X)(amid)] (4 examples) have been crystallographically characterised and subject to halide abstraction reactions. In one case, the cationic complex, [CpFe(CO)2Ga(OEt2){(CyN)2CBut}][BArf4], was isolated and crystallographically characterised. A hydrolysis product of this complex, [{CpFe(CO)2Ga[(CyN)2CBut]}2(micro-OH)][BArf4], was also isolated in low yield from this reaction and structurally characterised.

Journal Article↗
PubMed2006

Synthetic, structural and theoretical studies of amidinate and guanidinate stabilised germanium(I) dimers.

The neutral germanium(i) dimers, [{Ge(Piso)}(2)] and [{Ge(Giso)}(2)], Piso = [(ArN)(2)CBu(t)](-), Giso = [(ArN)(2)CNPr(i)(2)](-), Ar = C(6)H(3)Pr(i)(2)-2,6, which are stabilised by bulky amidinate and guanidinate ligands respectively, have been prepared by reduction of the corresponding germanium(ii) chlorides, [Ge(Piso)Cl] and [Ge(Giso)Cl]; theoretical studies suggest that the Ge-Ge bonds of [{Ge(Piso)}(2)] and [{Ge(Giso)}(2)] are associated with their HOMOs, whilst their LUMOs have substantial Ge-Ge pi-bonding character.

Journal Article↗
PubMed2006

Complexes of an anionic gallium(I) N-heterocyclic carbene analogue with group 14 element(II) fragments: synthetic, structural and theoretical studies.

The reactions of the anionic gallium(I) N-heterocyclic carbene (NHC) analogue, [K(tmeda)][:Ga{[N(Ar)C(H)]2}], Ar = C6H3Pri2-2,6, with the heavier group 14 alkene analogues, R2E=ER2, E = Ge or Sn, R = -CH(SiMe3)2, have been carried out. In 2:1 stoichiometries, these lead to the ionic [K(tmeda)][R2EGa{[N(Ar)C(H)]2}] complexes which exhibit long E-Ga bonds. The nature of these bonds has been probed by DFT calculations, and the complexes have been compared to neutral NHC adducts of group 14 dialkyls. The 4:1 reaction of [K(tmeda)][:Ga{[N(Ar)C(H)]2}] with R2Sn=SnR2 leads to the digallyl stannate complex, [K(tmeda)][RSn[Ga{[N(Ar)C(H)]2}]2], presumably via elimination of KR. In contrast, the reaction of the gallium heterocycle with PbR2 affords the digallane4, [Ga{[N(Ar)C(H)]2}]2, via an oxidative coupling reaction. For sake of comparison, the reactions of [K(tmeda)][:Ga{[N(Ar)C(H)]2}] with Ar'2E=EAr'2, E = Ge, Sn or Pb, Ar' = C6H2Pri3-2,4,6, were carried out and led to either no reaction (E = Ge), the formation of [K(tmeda)][Ar'2SnGa{[N(Ar)C(H)]2}] (E = Sn), or the gallium(III) heterocycle, [Ar'Ga{[N(Ar)C(H)]2}] (E = Pb). Salt elimination reactions between [K(tmeda)][:Ga{[N(Ar)C(H)]2}] and the guanidinato group 14 complexes [(Giso)ECl], E = Ge or Sn, Giso = [Pri2NC{N(Ar)}2]-, gave the neutral [(Giso)EGa{[N(Ar)C(H)]2}] complexes. All complexes have been characterized by NMR spectroscopy and X-ray crystallographic studies.

Anions↗
PubMed2006

The first complexes and cyclodimerisations of methylphosphaalkyne (P[triple bond]CMe).

The first complexes and cyclodimerisations of methylphosphaalkyne, P[triple bond]CMe, are reported to arise from its reactions with a range of platinum(0) complexes and [W(CO)5(THF)]. A number of differences between the chemistry of this phosphaalkyne and that of its bulkier analogues have been highlighted and explained on steric grounds.

Journal Article↗
PubMed2006

Complexes of a gallium heterocycle with transition metal dicyclopentadienyl and cyclopentadienylcarbonyl fragments, and with a dialkylmanganese compound.

The reactivity of several transition metal half sandwich complexes towards an anionic gallium(I) heterocyclic complex, [K(tmeda)][Ga{[N(Ar)C(H)]2}](Ar = C6H3Pri2-2,6), has been investigated. This has led to the anionic half sandwich complexes, [K(tmeda)][(C5H4R)M(CO)n[Ga{[N(Ar)C(H)]2}]](M = V, R = H, n= 3; M = Mn, R = Me, n= 2; M = Co, R = H, n= 1), which crystallographic studies show to form dimers (M = Mn and Co) or a polymer (M = V) through bridging potassium cations. The metal-gallium bond lengths in all complexes are very short which, combined with some spectroscopic evidence, is suggestive of M-Ga pi-bonding. Density functional theory studies of models of all complexes indicate that the level of back-bonding in these complexes is, however, minimal and of a similar order to that seen in analogous complexes incorporating neutral N-heterocyclic carbene ligands. Reactions of the metallocenes, [M(C5H4Me)2](M = V or Cr), with the digallane4, [Ga{[N(Ar)C(H)]2}]2, have afforded the neutral complexes, [M(C5H4Me)2[Ga{[N(Ar)C(H)]2}]], which are thought to be formed via an initial oxidative insertion of the transition metal centre into the Ga-Ga bond of the digallane. X-Ray crystallography shows the complexes to be monomeric. One (M = V) reacts with one equivalent of [K(tmeda)][Ga{[N(Ar)C(H)]2}] to give the crystallographically characterised, anionic bis(gallyl)-complex, [K(tmeda)][V(C5H4Me)2[Ga{[N(Ar)C(H)]2}]2]. For comparison, the reaction of [K(tmeda)][Ga{[N(Ar)C(H)]2}] with [Mn{CH(SiMe3)2}2] was carried out and gave the monomeric, anionic complex, [K(tmeda)][Mn{CH(SiMe3)2}2[Ga{[N(Ar)C(H)]2}]].

Journal Article↗
PubMed2006

Synthesis, structural characterization, and theoretical studies of complexes of magnesium and calcium with gallium heterocycles.

The magnesium- and calcium-gallium heterocycle complexes [Mg{Ga[(ArNCH)2]}2(THF)3] and [Ca{Ga[(ArNCR)2]}2(THF)4], R = H or Me, Ar = C6H3Pr(i)2-2,6, have been prepared via the reduction of [I2Ga{(ArNCR)2}] with the group 2 metal in tetrahydrofuran. The mechanisms of the reactions have been elucidated, and the crystal structures of the complexes exhibit the first structurally authenticated Ga-Mg and Ga-Ca bonds in molecular species. Theoretical studies suggest that the heterocycle-group 2 metal interactions have significant ionic character.

Journal Article↗
PubMed2006

Four-membered group 13 metal(I) N-heterocyclic carbene analogues: synthesis, characterization, and theoretical studies.

The synthesis, spectroscopic and structural characterization of the monomeric, four-membered group 13 metal(I) heterocycles ([:M{eta2-N,N'-(Ar)NC(NCy2)N(Ar)}], M = Ga or In, Ar = C6H3Pri2-2,6) and an isomeric thallium complex are reported. Theoretical studies on these complexes, which are analogues of four-membered N-heterocyclic carbenes, suggest they should act as good sigma-donor ligands.

Journal Article↗
PubMed2006

Dinuclear alkynyllanthanoid(II) dications with pentaphenylcyclopentadienyl or tri-tert-butyldiphosphacyclopentadienyl counter ions.

Reaction of [Yb(CpPh5)(C[triple bond]CPh)(thf)]2 (CpPh5 = pentaphenylcyclopentadienyl), prepared from Yb(C triple bond CPh)2 and HCpPh5 or Yb metal, HgPh(C[triple bond]CPh) and HCpPh5, with a controlled amount of diglyme (dig), and of Eu(C triple bond CPh)2, P triple bond CBut and dig, yield the unusual organolanthanoid(II) dicationic complexes [Yb(C[triple bond]CPh)(dig)(thf)2]2[CpPh5]2.4thf and [Eu(C triple bond CPh)(dig)2]2[P2C3But3]2 respectively.

Journal Article↗
PubMed2006

Amplitude range analysis of otolithic organ responses.

Benign paroxysmal positioning vertigo is easily diagnosed with the Dix-Hallpike maneuver. It is an ideal clinical condition in which to study the electrical response of the inner ear with electrocochleography techniques. Responses can be recorded during head tilt in roll and in pitch. With this technique we found that the amplitude range and scaling behavior of recorded raw data for the baseline resting position versus the stimulus position was statistically different in both patients and normal subjects. This can be demonstrated in the visual format of box plots. This technique promises to become a valuable addition to electrical examination techniques of the inner ear.

Adult↗
PubMed2005

The reactivity of gallium-(I), -(II) and -(III) heterocycles towards Group 15 substrates: attempts to prepare gallium-terminal pnictinidene complexes.

The reactivity of a series of Ga(I), Ga(II) and Ga(III) heterocyclic compounds towards a number of Group 15 substrates has been investigated with a view to prepare examples of gallium-terminal pnictinidene complexes. Although no examples of such complexes were isolated, a number of novel complexes have been prepared. The reactions of the gallium(I) N-heterocyclic carbene analogue, [K(tmeda)][:Ga{[N(Ar)C(H)](2)}] (Ar = 2,6-diisopropylphenyl) with cyclo-(PPh)(5) and PhN[double bond, length as m-dash]NPh led to the unusual anionic spirocyclic complexes, [{kappa(2)P,P'-(PhP)(4)}Ga{[N(Ar)C(H)](2)}](-) and [{kappa(2)N,C-PhNN(H)(C(6)H(4))}Ga{[N(Ar)C(H)](2)}](-), via formal reductions of the Group 15 substrate. The reaction of the digallane(4), [Ga{[N(Ar)C(H)](2)}](2), with (Me(3)Si)N(3) afforded the paramagnetic, dimeric imido-gallane complex, [{[N(Ar)C(H) ](2)}Ga{mu-N(SiMe(3))}](2), via a Ga-Ga bond insertion process. In addition, the new gallium(III) phosphide, [GaI{P(H)Mes*}{[N(Ar)C(H)](2) }], Mes* = C(6)H(2)Bu(t)(3)-2,4,6; was prepared and treated with diazabicycloundecane (DBU) to give [Ga(DBU){P(H)Mes*}{[N(Ar)C(H)](2)}], presumably via a gallium-terminal phosphinidene intermediate, [Ga{[double bond, length as m-dash]PMes*}{[N(Ar)C(H)](2) }]. The possible mechanisms of all reactions are discussed, all new complexes have been crystallographically characterised and all paramagnetic complexes have been studied by ENDOR and/or EPR spectroscopy.

Journal Article↗
PubMed2005

Synthesis and characterization of thermally robust amidinato group 13 hydride complexes.

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.

Journal Article↗
PubMed2005

Controlled decomposition of an indium trihydride adduct: synthesis and characterization of the first mixed-oxidation-state indium sub-halide complex anion, [In5Br8(quinuclidine)4]-.

The first example of a compound containing a mixed-oxidation-state indium sub-halide complex anion, [In5Br8(quinuclidine)4]-, has been accessed by the controlled decomposition of an indium trihydride adduct, [InH3(quinuclidine)], in the presence of LiBr. An intermediate in this reaction, [InH2Br(quinuclidine)2], has been isolated and suggests that its mechanism involves hydride-bromide exchange, reductive dehydrogenation, and disproportionation processes.

Journal Article↗
PubMed2005

Synthesis, characterisation and theoretical studies of amidinato-indium(I) and thallium(I) complexes: isomers of neutral group 13 metal(I) carbene analogues.

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}].

Amidines↗