149185-19-3Relevant academic research and scientific papers
Variable coordination modes of benzaldehyde thiosemicarbazones - Synthesis, structure, and electrochemical properties of some ruthenium complexes
Dutta, Swati,Basuli, Falguni,Castineiras, Alfonso,Peng, Shie-Ming,Lee, Gene-Hsiang,Bhattacharya, Samaresh
, p. 4538 - 4546 (2008)
Reaction of benzaldehyde thiosemicarbazones [H2LR, where H 2 stands for the two protons, the hydrazinic proton, and the phenyl proton at the ortho position, with respect to the imine function and R (R = OCH3, CH3, H, Cl, and NO2) for the para substituent] with [Ru(PPh3)2(CO)2Cl 2], carried out in refluxing ethanol, afforded monomeric complexes of type [Ru(PPh3)2(CO)(HLR)(H)]. The crystal structure of the [Ru(PPh3)2(CO)(HLNO2)(H)] complex was determined. The thiosemicarbazone ligand is coordinated to the ruthenium center as a bidentate N,S-donor ligand forming a four-membered chelate ring. When the reaction of the thiosemicarbazones with [Ru(PPh3)2(CO) 2Cl2] was carried out in refluxing toluene, a family of dimeric complexes of type [Ru2(PPh3) 2(CO) 2(LR)2] were obtained. The crystal structure of [Ru 2(PPh3)2(CO)2(LCl)2] was determined. Each thiosemicarbazone ligand is coordinated to one ruthenium atom, by dissociation of the two protons, as a dianionic tridentate C,N,S-donor ligand, and at the same time the sulfur atom is also bonded to the second ruthenium center. 1H NMR spectra of the complexes of both types are in excellent agreement with their compositions. All the dimeric and monomeric complexes are diamagnetic (low-spin d6, S = 0) and show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry of the [Ru(PPh3)2(CO)(HLR)(H)] and [Ru2(PPh 3)2-(CO)2(LR)2] complexes show the ruthenium(II)-ruthenium(III) oxidation within 0.48-0.73 V vs. SCE followed by a ruthenium(III)-ruthenium(IV) oxidation within 1.09-1.47 V vs. SCE. Potentials of both the oxidations are found to correlate linearly with the electron-withdrawing character of the substituent R. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
