Unsupported Au(i)⋯Cu(i) interactions: influence of nitrileligands and aurophilicity on the structure and luminescence

Abstract

The synthesis, structural characterization and the study of the photophysical properties of complexes [AuCu(C₆F₅)₂(NC–CH₃)₂] 1, [AuCu(C₆F₅)₂(NC–Ph)₂]₂2, and [AuCu(C₆F₅)₂(NC–CHCH–Ph)₂] 3 have been carried out. The crystal structures of complexes 1–3 consist of dinuclear Au–Cu units built from mediated metallophilic Au(I)⋯Cu(I) interactions. In the case of complex 2 two dinuclear units interact via an aurophilic interaction leading to a tetranuclear Cu–Au–Au–Cu arrangement. Complex 2 is brightly luminescent in solid state at room temperature and at 77 K with a lifetime in the nanoseconds range, while complexes 1 and 3 do not display luminescence under the same conditions. The presence of the aurophilic interaction in complex 2 seems to be responsible for the blue luminescence observed. DFT and time-dependent DFT calculations agree with the experimental results and support the idea that the origin of the luminescence of these complexes arise from orbitals located in the interacting metals.