Adducts of Mn and Re vinylidenes with P–OR nucleophiles: Hydrolysis rather than the intramolecular Michaelis–Arbuzov rearrangement

Chemistry of vinylidene complexes. XXV. Synthesis and reactions of binuclear µ-vinylidene RePt complexes containing phosphite ligands. Spectroscopic, structural and electrochemical study

“…Binuclear RePt complexes of the type Cp(CO) 2 RePt(-C=CHPh)L 2 [L = P(OPr i ) 3 (1a), P(OEt) 3 (2a), P(OPh) 3 (3a)] were isolated from reactions of Cp(CO) 2 Re=C=CHPh with Pt[P(OR) 3 ] 4 (R = Pr i , Et, Ph) in 63%, 61%, and 91% yields, respectively. The moderate yields of the complexes 1a and 2a were caused by side reactions of the starting rhenium vinylidene with free phosphites, produced by dissociation of Pt[P(OR) 3 ] 4 in the reaction mixture, that initially resulted in extremely sensitive to water zwitter-ionic byproducts Cp(CO) 2 Re-C( + P(OR) 3 )=CHPh that then hydrolyzed upon a chromatography of the reaction mixtures to give the corresponding  2 -phosphorylalkene complexes Cp(CO) 2 Re{ 2 -E-HC[P(O)(OR) 2 ]=C(H)Ph} (R = Pr i , Et) in 10 and 16% yields (Scheme 1) [30]. However, in case of Pt[P(OPh) 3 ] 4 the formation of the byproduct wasn't observed because of low nucleophilicity of P(OPh) 3 and low rate of its reaction with the rhenium vinylidene [30].…”