Different emissive properties in dithiolate gold(I) complexes as a function of the presence of phenylene spacers

A family of dinuclear neutral thiolate gold complexes of the type RPh2PAuS(C6H4)nSAuPPh2R (n = 2, 3), RPh2PAuS(C6H4)S(C6H4)SAuPPh2R, RPh2PAuSCH2(C6H4)2CH2SAuPPh2R where R represents a pyridine or a phenylene ring, has been prepared and fully characterized. X-ray crystallographic studies showed the presence of aurophilic interactions for those species bearing two phenylene spacers between the gold metal centers, leading to infinite chains. The complexes are emissive in the solid state. Theoretical calculations together with the photophysical analysis seem to indicate that the main excitations involved in the emissive processes are due to a mixture of ILCT transition involving the thiolate and the conjugated phenylene rings, and LL′CT transitions comprising the thiolate and the pyridine or phenyl from the phosphine fragment which contrast with the typical gold thiolate emission, LMCT from the thiolate fragment to the metal center