Thiocarbonylphosphorane and arsorane ligands.

Independently unstable thiocarbonylphosphorane or arsorane ligands SCAR 3 (A = P, As) are observed in the salts [W(η 2 - C , S -SCAR 3 )(CO) 2 (Tp*)]PF 6 [AR 3 = PCy 3 , PMe n Ph 3- n : n = 0, 1, 2, AsMePh 2 ; Tp* = tris(dimethylpyrazolyl)borate] which arise from the reactions of phosphonio- or arsoniocarbynes [W(≡CAR 3 )(CO) 2 (Tp*)] + with sulfur.