文摘
The benzaldehyde thiosemicarbazones are found to undergo oxidation at the sulfur center upon reaction with[Rh(PPh3)3Cl] in refluxing ethanol in the presence of a base (NEt3). A group of organorhodium complexes areobtained from such reactions, in which the oxidized thiosemicarbazones are coordinated to rhodium as tridentateCNS donors, along with two triphenylphosphines and a hydride. From the reaction with para-nitrobenzaldehydethiosemicarbazone, a second organometallic complex is obtained, in which the thiosemicarbazone is coordinatedto rhodium as a tridentate CNS donor, along with two triphenylphosphines and a hydride. Reaction of the benzaldehydethiosemicarbazones with [Rh(PPh3)3Cl] in refluxing ethanol in the absence of NEt3 affords another group oforganorhodium complexes, in which the thiosemicarbazones are coordinated to rhodium as tridentate CNS donors,along with two triphenylphosphines and a chloride. Structures of representative complexes of each type of complexeshave been determined by X-ray crystallography. In all of the complexes, the two PPh3 ligands are trans. All of thecomplexes show intense MLCT transitions in the visible region. Cyclic voltammetry on these complexes shows aRh(III)-Rh(IV) oxidation on the positive side of SCE. Redox responses of the coordinated thiosemicarbazones arealso displayed by all of the complexes.