Pt-195 NMR of heteropolymetallic complexes containing secondary dithioxamides as binucleating ligands

Monometallic [Pt{S-S2C2(NR)2H}2] (S-S2C2(NR)2H ) = κ2-S,S-S2C2(NR)2H ) bis-dialkyl-dithioxamidate, R = methyl, isoamyl, benzyl) and binuclear and trinuclear heterobimetallic complexes [Pt{S-S2C2(NR)2H}{í-S2C2(NR)2}MLn] (μ-S2C2(NR)2= κ2-S,S(Pt)-κ2-N,N(M)-S2C2(NR)2) and [Pt{{μ-S2C2(NR)2}MLn}2] (MLn+ = [(η3-allyl)palladium]+, [bis-(2-phenylpyridine)rhodium]+, [(η6-p-cymene)(chloro)ruthenium]+, [(1,4-cyclooctadiene)rhodium]+, [(pentamethylcyclopentadienyl)( chloro)rhodium]+) have been prepared and characterized. The progressive substitution of the residual amidic hydrogen in the [Pt{S-S2C2(NR)2H}2] complexes with a MLn+ metal fragment results in the deshielding of platinum nuclei, a red shift of the MLCT absorption maximum, and a decrease in the oxidation potential. Such behavior has been interpreted as a progressive electron shift from platinum to the binucleating ligands, the extent of which depends on the nature of MLn+ metal fragment.