Synthesis and optical properties of binuclear gold(I) complexes with bridging phosphine ligands: luminescence from intraligand and metal-centered excited states

The complexes Au₂Cl₂(P-P) with P-P=biphep (2,2^′-bis(diphenylphosphino)-1,1^′-biphenyl), binap (2,2^′-bis(diphenylphosphino)-1,1^′-binaphthyl) and xantphos (9,9^′-dimethyl-4,5-bis(diphenyl-phosphino)xanthene), were prepared and characterized by elemental analysis and ESI-MS. The solid compounds show a r.t. phosphorescence. While the binap complex emits from an intraligand (IL) triplet, the luminescence of the biphep complex originates from a metal-centered (MC) triplet which is presumably lowered by gold-gold interaction. The xantphos complex displays a dual phosphorescence. In this case, the emitting triplets are of the IL and MC type.