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The cocrystallization phenomenon of two different sized tetranuclear silver(I) clusters derived from a phosphinothiosemicarbazone ligand is studied to explain the factors that are involved in the nuclearity of silver thiosemicarbazone clusters. The thiosemicarbazone structure is shown to be extremely useful in studying the assembly of the discussed clusters.

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]

A cobalt(II) thiosemicarbazonate mesocate has been structurally characterized as an unexpected mixture of conformational and linkage isomers. Moreover, we have shown that the absence of a nitrogen atom in the spacer of the helicand ligand H2La, enables the assembly of an achiral mesohelical complex in the case of Co(ll) ions. [ABSTRACT FROM AUTHOR]