Tungsten (Z)-1,2-Diphosphite−Alkene and (E)-Vinyl−Phosphite Complexes from Phosphite Fischer Carbene Complexes

Pentacarbonyl acyl tungstates 1 react with 2-chloro-5,5-dimethyl-1,3,2-dioxaphosphorinane to give phosphite Fischer carbene complexes 2, which in very mild conditions readily lead to the corresponding tungsten (Z)-1,2-diphosphite−alkene tetracarbonyl complexes 3 via a dimerization process (R = aryl) or tungsten (E)-vinyl−phosphite pentacarbonyl complexes 4 via a 1,2-hydrogen shift (R = alkyl), respectively.