Chemistry of o-Xylidene-Metal Complexes. Part 3.' Tungsten o-Xylidene Complexes derived from Tetrachloro(oxo)tungsten(vl) ; X-Ray Crystal Structures of [~( C H 2 C 6 H 4~H z -o )~]~~.~~~~6 and [{~(CH2C,H4CH2=~)20}2~g(C4H*0)41*

Reaction of WCI4O with the di-Grignard reagent O-C&(CH2MgC1)2 or the chloride-free ' o-xylidene ' complex Mg(CH2C6H4CH2-o) (thf) in tetrahydrofuran (thf) yields either the thermally stable tris(chelate), [We use the umbrella term ' o-xylidenemetal complex ' to describe, without prejudice as to bonding, all O-C~I&(CH~)~-metal complexes in which the organic ligand binds in (a) a bridging mode, as i

Nonclassical Organolanthanoid Metal Chemistry: [K([18]-crown-6)( h 2-PhMe)2]X (X=[(LnCpt3)2( m -H)] [(LnCp''2)2( m - h 6: h 6-PhMe)]) from [LnCpx3]K and [18]-crown-6 in Toluene (Ln=La Ce; Cpt = h 5-C5H4SiMe2But;Cp'' = h 5-C5H3(SiMe3)2-13)

Internal_Co_Author1 = YK Gun'k

Crystalline (NN)C-M(NN) complexes: synthesis structure bonding and lability [M = Si Ge Sn or Pb; (NN) = 12-(ButCH2N)2C6H4]

Each of the red-brown or red, isomorphous, crystalline adducts (NN)C–M(NN) [(NN) = 1,2-(ButCH2N)2C6H4 and M = Si, Ge, Sn or Pb] has been obtained from the carbene (NN)C and the appropriate silylene, germylene, stannylene or plumbylene M(NN) in benzene and crystallisation from a hydrocarbon. They are monomeric, with the three-co-ordinate Ccarb and M atoms in an almost planar (C) or pyramidal (M) environment. The C–M distances are more than ca. 10% longer than for a typical MII–C bond in an MR2 molecule. Variable temperature 13C and xM NMR spectra (xM = 29Si, 119Sn or 207Pb) in toluene-d8, as well as for the appropriate M(NN) and C(NN) precursors, have been recorded. The Ccarb and M chemical shift data show that the compounds readily dissociate in solution, their stability decreasing in the sequence Sn > Pb > Si > Ge. From the magnitude of the chemical shifts, their conformation and C–M distances of the adducts, it is concluded that the C–M bond in each adduct is best formulated as being electrostatic in nature, with the carbene moiety as electron donor and the M(NN) fragment as acceptor

Unsaturated σ-hydrocarbyl transition-metal complexes. Part 2. Synthesis and reactions of vinylplatinum complexes and a comparison with analogous fluorovinyl and alkynyl complexes

Alkenyl (CHCH2 or CFCF2) or alkynyl (CCPh) derivatives of trimethyltin are shown to be superior to lithium or magnesium reagents for the synthesis of corresponding mono-organoplatinum(II) species by metathesis (L = SnMe3R +cis-[PtCl2L2]→trans-[PtRClL2]+ SnMe3Cl tertiary phosphine). The reactivity order for SnMe3R is R = CCPh > CFCF2 > CHCH2. This order is also found for oxidative addition of SnMe3R to Pt0 to give cis-[PtRL2(SnMe3)]. When the latter complex (R = CHCH2) reacts with X2 or MeX further oxidative addition occurs exclusively at the platinum centre. Aromatic isonitriles (R′NC)co-ordinate to the platinum and give insertion products trans-[Pt{C(CHCH2)= NR′}ClL2] on heating or carbene complexes with NBunH2. The alkynyl trans-[Pt(CCPh)ClL2] also forms 1 :1 adducts with R′NC and carbene complexes therefrom, but no insertion products. Spectroscopic data for the new complexes are presented