Reactions of benzene based half sandwich ruthenium(II) complex with 2,6-bis((phenylseleno)methyl)pyridine: Preferential substitution of ring resulting in a catalyst of high activity for oxidation of alcohols

[2,6-Bis((phenylseleno)methyl)pyridine] (L) a (Se, N, Se) pincer ligand synthesized by reacting PhSe- (in situ generated) with 2,6-bis(chloromethyl)pyridine reacts with [{(eta(6)-C6H6)RuCl(mu-Cl)}(2)] (2:1 molar ratio) by preferential substitution of ring resulting in the first Ru-(Se, N, Se) pincer ligand complex, mer-[Ru(CH3CN)(2)Cl(L)] [PF6](1).H2O. Similar reaction in 4:1 molar ratio results in mer-[Ru(L)(2)][ClO4](2)(2). The H-1, C-13{H-1) and Se-77(H-1) NMR spectra of L, 1 and 2 were found characteristic. The single crystal structures of 1 and 2 were studied by X-ray crystallography. The geometry of Ru in both the complexes is distorted octahedral. The Ru-Se distances are in the ranges 2.4412(16)-2.4522(16) and 2.4583(14)-2.4707(15) angstrom respectively for 1 and 2. The structural solutions from the crystal data in case of 2, due to inferior quality of its crystals, are suitable for supporting bonding mode of L with Ru(II) only. The 1 shows high catalytic activity for oxidation of primary and secondary alcohols (TON up to 9.7 x 10(4)). (C) 2010 Elsevier B.V. All rights reserved.