Luminescent heterometallic gold–copper alkynyl complexes stabilized by tridentate phosphine

Abstract

The reactions between trinuclear gold complex tppmAu₃Cl₃ (tppm = tris(diphenylphosphino)methane), arylacetylenes HC₂C₆H₄X and Cu⁺ under basic conditions result in formation of the heterometallic complexes [tppm(AuC₂C₆H₄X)₃Cu]⁺, X = H (1), COOMe (2), CN (3), OMe (4), NH₂ (5). These compounds belong to one structural motif and consist of the heterometallic {(AuC₂C₆H₄X)₃Cu} core stabilized by the tridentate phosphine. Compounds 1–5 were characterized by polynuclear NMR and IR spectroscopy, ESI-MS and single-crystal X-ray analysis. Luminescence properties of these complexes have been studied and revealed a substantial red shift of the emission maxima with the increase in the electron donicity of the alkynyl ligands substituents in the 550–680 nm range. The theoretical calculations of the electronic structures showed that variations of the substituents on the alkynyl ligands display very little effect on the molecular structural parameters but show appreciable influence on the orbital energies and luminescence characteristics of the compounds under study.