Metalloligands: Rhodium(III) Cyclometallated Compounds Containing Multitopological Binucleating Ligands

The reaction of [Rh(2-phenylpyridine)2Cl]2 with secondary dithiooxamides H2R2C2N2S2 (R = isoamyl, iso-Pr, {S}-phenylethyl, meso-phenylethyl) affords the contact ion pair [Rh(2-phenylpyridine)2(H2R2C2N2S2 kappa-S,S-Rh)]+Cl-, which can be transformed into the neutral complexes [Rh(2-phenylpyridine)2(HR2C2N2S2 kappa-S,S-Rh)]. The HCl exchange between the ion pairs and the corresponding neutral complexes has been studied by dynamic NMR spectroscopy techniques, and a mechanism for this exchange has been proposed. [Rh(2-phenylpyridine)2{H(isoamyl)2C2N2S2 kappa-S,S-Rh}] reacts with chlorido-bridged dimers [MLnCl]2 {MLn = Pd(eta3-allyl), Rh(cyclooctadiene), (n-propyl)3PClPd} and provides the heterobimetallic complexes [Rh(2-phenylpyridine)2{mu-(isoamyl)2C2N2S2}MLn]. Heterobimetallic complexes having the same formula and the same structure are obtained by reaction of [MLn{H(isoamyl)2C2N2S2 kappa-S,S-M}] species [MLn = Rh(1,5-cyclooctadiene), Pd(eta3-allyl), PdCl(tri-n-propylphosphane), PtCl(diphenyl-2-pyridylphosphane)] with [Rh(2-phenylpyridine)2Cl]2. The connectivity of the binucleating ligand diisoamyldithiooxamidate within the bimetallic complexes has been assessed. The linkage isomer obtained is [Rh(2-phenylpyridine)2{mu-(isoamyl)2C2N2S2}MLn] (kappa-N,N-RhIII, kappa-S,S-M).