A homoleptic AgIII complex stabilized by succinimidate ligands.

Abstract

Herein, the first example of a homoleptic AgIII complex stabilized by a monodentate N-donor ligand is presented. Na2[S2O8] oxidizes the linear AgI complex, Na[Ag(succ)2] (1Na), to form a square planar argentate(iii) ion, [Ag(succ)4]-, which crystallizes with a polymeric chain-structure, M[Ag(succ)4] (2M), when treated with alkali metal sulfate M2SO4 (M = K, Rb, Cs). A mixed-valent Robin-Day class I system, [(H2O)Ag][Ag(succ)4] (2Ag), forms in the absence of K+/Rb+/Cs+ ion. Diamagnetic 2Cs displays a succinimide C[double bond, length as m-dash]O stretching frequency at higher energy than does the isoelectronic PdII complex, [(H2O)Na]2[Pd(succ)4] (3Na). Moreover, 2Cs displays UV-vis absorptions that are more intense and occur at lower energy than those in 3Na. The electron-deficient nature of 2Cs is further evident from its ability to oxidize water to O2. From 109Ag magic-angle spinning NMR studies, a highly deshielded AgIII environment in 2Cs (2080 ppm) relative to the AgI starting material 1Na (492 ppm) is observed.