Synthesis, characterization and structure of ruthenium(II) phosphine complexes with N-heterocyclic thiolate ligands

The [Ru(dppb)(mbt)(2)], mbt = 2-mercaptobenzothiazole, complex, isolated from the reaction of the mer-[RuCl3(dppb)(OH,)] complex with the 2,2'-dithiobis(benzothiazole), mbts, was characterized by spectroscopic and electrochemical techniques (E-1/2 = 0.78 V versus NHE) and its structure was determined by crystal X-ray analysis. The structural analysis suggests that the S-S bond of the mbts ligand is cleaved, thus forming two four-membered chelate rings coordinated to the ruthenium through the N,S-donor atoms of the mbt reduced ligands, with an average bite angle of 67.295(11)degrees. The H-1 and C-13 NMR signals observed for mbts ligand coordinated to the metal center, the changes in the vibrational spectra, and the appearance of a MLCT band in the electronic spectrum of the complex point for the reduced state of the ruthenium metal center, Ru-II. These reducing processes are suggested to be due to the methanol interference, which is observed to be strongly affected by N-methylmorpholine. The cytochrome c electrochemistry was analyzed by using the SAMs formed by the mbts and the [Ru(dppb)(mbt)(2)] complex on gold, with only the former presenting electroactivity. (c) 2005 Elsevier B.V. All rights reserved.