Metal complexes of Group 1B. Part 1. Triphenylphosphinesilver(I) carboxylates

Abstract

An investigation has been made into the mode of co-ordination of carboxylic acids with Ag^I. From a study of the ¹H n.m.r. and i.r. spectra and solution molecular weights the silver atoms in the complexes are all four-co-ordinate but the stoicheiometry depends on the pK_a of the acid. All the acids studied form complexes of stoicheiometry [Ag(O₂CR)(PPh₃)₂](R = Me, CH₂Cl, CHCl₂, Ph, C₆H₄Me-o, C₆H₄Me-m, or C₆H₄OH-o). In addition, for acids having pK_a > 3.9 (i.e. R = Me, Ph, C₆H₄Me-o, or C₆H₄Me-m) chelation of the acid to the silver results in a complex of storcheiometry [Ag(O₂CR)(PPh₃)₂]. The two dibasic acids studied, adipic and malonic, show a similar pK_a dependence.