Synthesis and characterization of ruthenium(III) complexes with para-and meta-substituted benzenseleninic acids as ligands

A number of complexes of ruthenium(III) with para- and meta-substituted benzeneseleninic acids, XC6H4SeO2H (X = H, m-Br, p-Br, p-CH3, m-Cl, p-Cl) are reported. The recently prepared compounds are characterized through elemental analyses, near and far i.r. spectroscopy, electronic spectra, conductivity measurements, thermal analyses (TG and DTG) and magnetic susceptibility measurements. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of the crystal field theory; the nephelauxetic parameters are all indicative of an appreciable metal-ligand covalency. The i.r. results point to a O, O′-seleninato coordination for all the complexes; in particular the presence of three SeO bands with the irreducible representation A2 + 2E in the i.r. spectra of the trisderivatives of the type Ru (XC6H4SeO2)3 suggests an octahedral configuration with D3 symmetry. The complexes of the type Ru (XC6H4SeO2)2 Y (Y = Cl, Br) are polymeric octahedral with bridging halides.