eta(2)(3e)-vinyl complexes and one-electron-transfer reactions: tris(pentafluorophenyl)borane as a one-electron oxidant

The eta (2)(3e)-vinyl complex [Mo{=C(Ph)CHPh}{P(OMe)(3)}(2)Cp] is oxidized by [FeCp2](+), [CPh3](+), or B(C6F5)(3) to form the 17-electron. cation [Mo {=C(Ph)CHPh}{P(OMe)(3))(2)Cp](+) which on warming loses H to form the catio nic eta (2)(4e)-alkyne complex [Mo(eta (2)-PhC CPh){P(OMe)(3))(2)Cp](+). In the case of the borane there is evidence for a competing reaction between the eta (2)-vinyl complex and the acid (H2O)B(C6F5)(3), a resulting in the formation of a labile trans-stilbene complex.