μ-Halo bridged binuclear ruthenium(III) complexes featuring pyridazine ligands: Synthesis, structure, spectral and electrochemical properties

The reaction of [RuX3(AsPh3)(3)] and N,N-disubstituted pyridazine-3,6-diamine in benzene under reflux afford novel binuclear, halo-bridged, ruthenium(III) complexes with the general formula [Ru-2(AsPb3)(2)(mu-X)(2)X-4(L)] (X = Cl or Br; L = N,N-disubstituted pyridazine-3,6-diamine). All the complexes have been characterized by elemental analysis, spectral (UV-Vis, EPR) and electrochemical methods (CV, DPV). The electronic spectra of the complexes indicate the presence of d-d and intense LMCT transitions in the visible region. The molecular structure of one of the complexes (2) has been determined by X-ray crystallography, which indicates the bridging coordination of the pyridazine in these binuclear complexes. In complex (2) each metal has a distorted octahedral NCl4As coordination sphere constituted by the two exogenous bridging chlorides. The complexes are paramagnetic (low spin, d(5)) in nature and all the complexes at 77 K show rhombic distortion around the ruthenium ion with three different 'g' values (g(x) not equal g(y) not equal g(z)). All the complexes exhibit two quasi-reversible one electron reductive responses (Ru-III-Ru-III/Ru-II-Ru-III; Ru-II-Ru-III/Ru-II-Ru-II) within the E-1/2 range of -0.68 to -0.78v and -1.25 to -1.33 V. respectively, versus SCE. (C) 2012 Elsevier Ltd. All rights reserved.