Syntheses and dynamic stereochemistry of methyl–and phenyl–carbonyl heterobinuclear metal–metal bonded complexes

Abstract

The bimetallic complexes [ML_nPtMe(PPh₃)₂][ML_n= Mo(CO)₃(η-C₅H₅), W(CO)₃(η-C₅H₅), Mn(CO)₅, or Co(CO)₄] and [ML_nPtPh(PPh₃)₂][ML_n= Mo(CO)₃(η-C₅H₅) or W(CO)₃(η-C₅H₅)] have been prepared by the reaction of the in situ generated [Pt(OClO₃)R(PPh₃)₂](R = Me or Ph) with the appropriate carbonylmetalate anions. The complexes [(η-C₅H₅)(CO)₃MoPtMe(PPh₃)₂] and [(η-C₅H₅)(CO)₃WPtMe(PPh₃)₂] show low-temperature ³¹P n.m.r. spectra consistent with a cis structure. A reversible, mutual exchange process is observed upon warming, but already at room temperature, solutions of [(η-C₅H₅)(CO)₃MoPtMe(PPh₃)₂]show a cis-trans isomerization process. In contrast, the other bimetallic complexes are rigid in solution, displaying a trans configuration.