Synthesis and characterization of ruthenium(II) azoimine-diphosphine mixed-ligand complexes

A novel family of the general type cis-[Ru-II(dppe)LCl2] {L=C6H5N=NC(COCH3)=NAr, Ar= 2,4,6-trimethylphenyl(L-1), 2,5-dimethylphenyl(L-2), 4-toly(L-3), phenyl(L-4), 4-methoxyphenyl(L-5), 4-chlorophenyl(L-6), 4-nitrophenyl (L-7), 2,5-dichlorophenyl (L-8); dppe=Ph2P(CH2)(2)PPh2} has been synthesized. These complexes have been characterized through analytical, spectroscopic (IR, UV-Vis, and NMR) and electrochemical (cyclic voltammetry) techniques. In addition, complex 4 (where L = L-4) has been further characterized by X-ray diffraction analysis. Crystallographic, electrochemical and electronic spectral data are all consistent with the azomethine ligands possessing strong pi-acceptor properties. These pi-acceptor properties can be "tuned" by a judicious choice of substituent on the azomethine ligand. (C) 2008 Elsevier Ltd. All rights reserved.