Solvent and counter ion effects in bis(imidazole) dinuclear heterometallacyclic complexes of gold(I): Some considerations of porosity

Cyclic 2:2 complexes of AuI and bitmb [1,3-bis(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene] were prepared and the structures of [Au2(μ-bitmb)2](BF4)2·2CH3CN (1·2CH3CN), [Au2(μ-bitmb)2](BF4)2·2CH2Cl2 (1·2CH2Cl2) and [Au2(μ-bitmb)2](CF3SO3)2·2CH2Cl2 (2·2CH2Cl2) were determined by single crystal X-ray diffraction. The frameworks of the compounds consist of dicationic rectangular heterometallacycles linked by aurophilic interactions along the b axis and edge-to-face C–H⋯π contacts. The latter expand the structures in zigzag fashion along the a axis leading to a 3D assembly. Interactions between the counterions and imidazole rings are also present in all structures. When crystals of 2·2CH2Cl2 are subjected to a dynamic vacuum at 90 °C remarkably only 1 mol equivalent of CH2Cl2 is removed, but without loss of crystallinity, affording the structure of 2·CH2Cl2.