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

A novel family of the general type cis-[RuII(dppe)LCl2] {L = C6H5N{double bond, long}NC(COCH3){double bond, long}NAr, Ar = 2,4,6-trimethylphenyl (L1), 2,5-dimethylphenyl (L2), 4-tolyl (L3), phenyl (L4), 4-methoxyphenyl (L5), 4-chlorophenyl (L6), 4-nitrophenyl (L7), 2,5-dichlorophenyl (L8); dppe = Ph2P(CH2)2PPh2} 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 = L4) has been further characterized by X-ray diffraction analysis. Crystallographic, electrochemical and electronic spectral data are all consistent with the azomethine ligands possessing strong π-acceptor properties. These π-acceptor properties can be "tuned" by a judicious choice of substituent on the azomethine ligand