A copper(II)-copper(II) bond in a dimeric molecule of a mineral

Copper(II) acetate monohydrated, mineral hoganite, shows a dimeric structure with four acetate residuals bridging a metal-metal moiety. The ferromagnetism of the compound has been attributed to spin pairing obtained either through a direct Cu(II)-Cu(II) bond or through the carboxylate ligands. A low temperature (100K) X-ray data collection and a subsequent multipolar analysis has supplied maps of electron densities. The topological study of the maps revealed the presence of a direct metal-metal bond, which has been confirmed by theoretical DFT calculations on the isolated molecule. Experimental and theoretical topological parameters will be reported.