Trapping of Cp*W(NO)(eta(2)-PhC CH), the key intermediate in the C-H activation of alkanes by Cp*W(NO)(CH2SiMe3)(CPh=CH2)

Thermolysis of the vinyl nitrosyl complex Cp*W(NO)(CH2SiMe3)(CPh=CH2) (1) in ethyl acetate or acetonitrile affords the oxa- or azametallacycles Cp*W(NO)(eta(2)-OC(Me)(OEt)CH=CPh) (2) or Cp*W(NO)(eta(3)-HNC(Me)=NC(=CH2)CH=CPh) (3) and Cp*W(NO)(OH)(eta(2)-HN=C(Me)CH=CPh) (4), respectively. Kinetic and mechanistic studies provide compelling evidence for a pathway involving initial rate-limiting unimolecular elimination of SiMe4 from 1 with concomitant formation of Cp*W(NO)(eta(2)-CPh=CH), (A).