Formation and reactivity of a cationic alkylidene-aryl complex of tungsten

Oxidatively Induced Abstraction Reactions. A Synthetic Approach to Low-Coordinate and Reactive Early Transition Metal Complexes Containing Metal−Ligand Multiple Bonds

“…23 Oxidatively induced R-hydrogen abstraction reactions to generate reactive MdC bonds can be traced back to the work by Cooper and co-workers (referred to as an H atom transfer). 24 However, it was not until 1995 that McCamley and co-workers trapped a transient niobium alkylidene by a redox route. 25 Their studies described the one-electron oxidation of Nb(IV)-(η 5 -C 5 H 4 t Bu) 2 (CH 2 Ph) 2 with AgBPh 4 to generate a Ag 0 mirror along with the kinetically unstable benzylidene [Nb(V)(η 5 -C 5 H 4 t Bu) 2 (CHPh)][BPh 4 ] salt.…”

Synthesis and characterisation of cationic bis(cyclopentadienyl)tungsten(IV) complexes containing alkyl, chloride and hydride ligands

“…* * A related complex may be prepared indirectly from [W(q-C,H,),Me(Ph)]; upon oxidation, the 17-electron cation [W(q-C,H,),Me(Ph)]+ is formed, which may be reduced by the trityl radical in acetonitrile to w(q-C,H,),(CH,Ph)(NCMe)] + . 29 It seems likely that oxidation of 8 yields [W(q-C,H,),(H)Cl]+ as a transient intermediate which, in the presence of donor nitrile ligands, eliminates hydrogen and leads to [W(q-C,H,),Cl(NCR)] + cations. We have not been able to effect the abstraction of chloride ion from 8 using silver salts.…”

η6-Tetramethylfulvene and μ-η3:η3-Benzene Complexes of Iridium

“…The tetramethylfulvene ligand of fulv-Ir + results from formal hydride transfer from the Cp* ligand of Ir-Me 2 to [CPh 3 ] + . On the basis of Cooper’s examination of reactions between trityl cation and (Cp) 2 W(Me)(R) (R = Me, Ph), we postulate initial one-electron oxidation of Ir-Me 2 by [CPh 3 ] + [B(C 6 F 5 ) 4 ] − (Scheme , step 1). This is followed by H atom transfer from the Cp* ligand of [Cp*Ir(NHC)Me 2 ] + to the triphenylmethyl radical to afford fulv-Ir + and HCPh 3 (Scheme , step 2).…”