Metallo Dioxaphospholanes with Metal to Phosphorus Single and Double Bonds

Metallo dioxaphospholanes Cp(CO) 3 M-POCMe 2 CMe 2 O (M=Cr, Mo, W) 1, which contain the σ-bound metal ligand in a pseudo axial position at the pyramidally configurated phosphorus, are obtained by a nucleophilic metallation of 1-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane with the anions Na[M(CO) 3 Cp] (M=Cr, Mo, W). 1 (M=W) is highly reactive towards quaternisation with MeI and oxidation with elementary sulfur, which reactions yield [Cp(CO) 3 W-P(Me)OCMe 2 CMe 2 O]I 2 and Cp(CO) 3 W-P(S)OCMe 2 CMe 2 O 3, respectively. Exchange of CO against P(OMe) 3 affords Cp(CO) 2 [P(OMe) 3 ]W-POCMe 2 CMe 2 O 4, which rapidly rearranges to Cp(CO) 2 -[P(O)(OMe) 2 ]W-P(Me)OCMe 2 CMe 2 O 5 via an O-P methyl group shift.