Dicarbonyl(eta5-cyclopentadienyl)(triethyl- or triphenylphosphine)(eta
1-methylthiovinyl)tungsten reacts with an equimolar amount of tetraflu
oroboric acid to yield the corresponding cationic thiocarbene complex
[CP(CO)2(PR3)W=C(Me)SMe][BF4] (R = Et, Ph).