The Simple Yet Elusive Crystal Structure of Silver Acetate and the Role of the Ag−Ag Bond in the Formation of Silver Nanoparticles during the Thermally Induced Reduction of Silver Carboxylates

Abstract

We report the single-crystal X-ray structure of silver acetate, accompanied by Raman spectra and density functional theory calculations. This work should aid understanding of the process of forming silver nanoparticles during the thermally induced reduction of silver carboxylates, e.g., in thermographic materials. The structure of silver acetate comprises the often-observed Ag2(carboxylate)2 dimer unit connected by interdimer Ag−O bonds to form infinite chains that align in a parallel fashion, forming stacks. The presence in the dimer of a Ag−Ag bond via closed-shell d10−d10 interactions is determined by Atoms in Molecules methodology, tentatively supported by the experimental observation of Raman scattering peaks (also found by vibrational frequency calculations) for Ag−Ag stretching. The Ag(I)−Ag(I) bond may be an important precursor to metallic silver formation, as single-electron reduction of the Ag2(carboxylate)2 species could result in the formation of (Ag2)+•, known in photographic chemistry as a precursor to metallic silver clusters. The calculated structure of the radical anion of silver acetate consists of a (Ag2)+• cluster complexed by two acetate ions, lending support to earlier postulates that Ag−Ag bonding may promote the formation of silver nanoparticles during the thermally induced reduction of silver carboxylates.