Silver(I) and gold(I) complexes with bitriazole-based N-heterocyclic carbene ligand: Solid state features and behaviour in solution

The coordinating properties of the bis(1,4-dimethyl-1,2,4-triazol-5-ylidene) ligand (abbreviated as bitz) towards silver(I) and gold(I) centres have been explored. The bitz behaves as bridging ligand giving both dinuclear [M2(bitz)2](PF6)2 and trinuclear [M3(bitz)3](PF6)3 species, whose formation has been supported by X-ray diffraction analysis, NMR spectroscopy and mass spectrometry evidences. The dinuclear and trinuclear gold(I) complexes present very similar luminescence properties, emitting in the blue region, at ~450 nm, when excited at 350 nm. Selected experimental aspects dealing with the synthesis of the dinuclear and trinuclear species, as well as with the absorption properties of the gold(I) complexes, have been investigated also through relativistic DFT calculations.