188649-53-8Relevant academic research and scientific papers
Synthesis and reactivity of tungsten (II) methylene complexes
Gunnoe, T. Brent,Surgan, Matthew,White,Templeton,Casarrubios, Luis
, p. 4865 - 4874 (1997)
Treatment of the methyl complex Tp′(CO)(PhC2Me)W-Me (1) or Tp(CO)(PhC2Ph)W-Me (2) with trityl cation yields the corresponding methylene complex [Tp′(CO)(PhC2Me)W=CH2]-[PF6] (3) (Tp′=hydridotris-(3,5-dimethylpyrazolyl)borate) or [Tp(CO)(PhC2Ph)W=CH2][PF6] (4) (Tp = hydridotris(pyrazolyl)borate). The carbene complex (3) is unusually persistent for a methylene complex. Complexes 3 and 4 display electrophilic behavior, as evidenced both by addition of nucleophiles and by methylene transfer to electron rich olefins. When bound to either carbene 3 or 4, arylimines are activated toward nucleophilic attack by ethyl diazoacetate (EDA). The net result of the addition of excess arylimine followed by excess EDA to a solution of either 3 or 4 is catalytic aziridine formation. X-ray diffraction studies have revealed the structures of [Tp′(CO)(PhC2Me)W-CH2PMe3][PF 6] (7) and [Tp′(CO)(PhC2-Me)W-CH2N(Me)=C(H)(Ph)][PF 6](15). The relative stabilities of 3 and 4 are discussed as well as the mechanism of aziridine catalysis.
