Benzothiazolethione complexes of coinage metals: from mononuclear complexes to clusters and polymers

The reactions of 2(3H)-benzothiazolethione (Hbtt) with [AuCl(tetrahydrothiophene)] and CuBr2 were studied, and found to yield a tetranuclear cluster compound [Au(btt)]4 [1] and a polymeric structure [CuBr(btt-btt)]n.nTHF (2). Crystallographic and spectroscopic methods were used for the characterization. In 1, the monoanionic ligand acted as a bidentate bridging N,S-donor giving a molecular cluster structure of an asymmetric coordination isomer. In the formation of 2, the ligand was dimerized by forming a S–S bond after deprotonation, and coordination via nitrogen donors to metal atoms took place leading to a polymeric structure. To clarify the diversity of reactions of Hbtt with coinage metals, and to verify the experimental characterization, DFT studies were performed. The nature of the coordination of the Hbtt ligand was further investigated via topological charge density analysis by QTAIM methods.