Strong intra- and intermolecular aurophilic interactions in a new series of brilliantly luminescent dinuclear cationic and neutral au(I) benzimidazolethiolate complexes.

The structural and photophysical properties of a new series of cationic and neutral Au(I) dinuclear compounds (1 and 2, respectively) bridged by bis(diphenylphosphino)methane (dppm) and substituted benzimidazolethiolate (X−BIT) ligands, where X = H (a), Me (b), OMe (c), and Cl (d), have been studied. Monocationic complexes, [Au2(μ-X−BIT)(μ-dppm)](CF3CO2), were prepared by the reaction of [Au2(μ-dppm)](CF3CO2)2 with 1 equiv of X−BIT in excellent yields. The cations 1a−1d possess similar molecular structures, each with a linear coordination geometry around the Au(I) nuclei, as well as relatively short intramolecular Au(I)···Au(I) separations ranging between 2.88907(6) A for 1d and 2.90607(16) A for 1a indicative of strong aurophilic interactions. The cations are violet luminescent in CH2Cl2 solution with a λemmax of ca. 365 nm, assigned as ligand-based or metal-centered (MC) transitions. Three of the cationic complexes, 1a, 1b, and 1d, exhibit unusual luminescence tribochromism in the solid-state, in which ...