Very Short Metallophilic Interactions Induced by Three-Center–Two-Electron Perhalophenyl Ligands in Phosphorescent Au–Cu Complexes

Abstract

The synthesis, structural characterization, and study of the photoluminescent properties of the complexes [Au3Cu(C6F5)4(N≡CCH═CHPh)3]n (1) and [Au2Cu(C6Cl5)3(N≡CCH═CHPh)2] (2) have been carried out. The crystal structures of complexes 1 and 2 display a common [Au2Cu(C6X5)2(μ-C6X5)(NCCHCHPh)2] fragment built up through a trinuclear Au2Cu unit with a perhalophenyl group acting as a three-center–two-electron bridging ligand. In the case of 1 an additional [Au(C6F5)(NCCHCHPh)] unit is also present in the asymmetric unit. Both complexes are brightly luminescent in the solid state at room temperature and at 77 K with lifetimes in the nanosecond range for 1 and in the microsecond range for 2. The presence of very short metallophilic interactions seems to be responsible for the low-energy luminescence observed. DFT and time-dependent DFT calculations agree with the experimental results and support the idea of that the origin of the emissions arises from metal-based orbitals and arrive at ligand-based orbitals as ...