Novel Fluorescent Cationic Silver Thiosemicarbazone Clusters Containing Different Eight-Membered Ag4S4 Metallacycles.

The reaction of silver acetate and silver nitrate with the new phosphinethiosemicarbazone ligand 2-(2-(diphenylphosphino)benzylidene)-N-ethylthiosemicarbazone (HLPEt) gave rise to the complexes [Ag(LPEt)][sub4]∙2MeOH (1) and [Ag[sub2](LPEt)(HLPEt)][sub2]∙(NO3)2 (3). Slow crystallization of the mother liquors obtained from the synthesis of 1 and 3 afforded suitable crystals of [Ag[sub2](LPEt)(HLPEt)][sub2](CH[sub3]COO)[sub2]∙6MeOH (2) and [Ag[sub2](LPEt)(HLPEt)][sub2](NO[sub3])[sub2]∙2MeOH∙2H[sub2]O (4), respectively. Complexes 2 and 4 are tetranuclear silver clusters displaying a similar Ag[sub4]S[sub4]P[sub4] core, but containing different sizes, conformations for the Ag[sub4]S[sub4] metallacycles, and crystal packings. The four complexes are strongly luminescent in methanol solutions. A comparison between the emission bands of compounds 1-4 lead us to conclude that the luminescence is notably affected by the charge and the counterion of the cluster. [ABSTRACT FROM AUTHOR]