Role of C-H•••Au and Aurophilic Supramolecular Interactions in Gold-Thione Complexes

The role of noncovalent gold-hydrogen and aurophilic interactions in the formation of extended molecular systems of gold complexes was studied. Three new gold compounds with a heterocyclic thione ligand N-methylbenzo-thiazole-2-thione (mbtt), namely, [AuCl(mbtt)] (1), [AuBr(mbtt)] (2), and [Au(mbtt)(2)] [AuI2](1-n)[I-3](n) (3), were synthesized and characterized. The halide ligand had a considerable effect on the complex structures and thus to noncovalent contacts. Intermolecular C-H center dot center dot center dot Au and aurophilic Au center dot center dot center dot Au contacts were the dominant noncovalent interactions in structures 1-3 determining the supramolecular arrays of the gold complexes. In 1 and 2, unusual intermolecular C-H center dot center dot center dot Au gold-hydrogen contacts linked the adjacent mononuclear molecules to a chain structure, while in 3 the change in the ligand coordination induced the formation of an intermolecular aurophilic interaction. Au center dot center dot center dot I, pi-pi, halogen-halogen, and hydrogen bonding interactions supported further the supramolecular array of 3. The interactions were analyzed with theoretical calculations using the Quantum Theory of Atoms in Molecules (QTAIM). The results thus obtained were consistent with the experimental data clarifying both the nature and the role of noncovalent interactions in structures 1-3.