Ligand effects on metal-oxygen stretching frequencies in dioxomolybdenum(VI) complexes

Abstract

Several new seven-coordinated dioxomolybdenum(VI) heterochelates, [MoO2(AA)(BBB)], where AA = bidentate ligand = ethylenediamine, 2-aminoethylpyridine, o-pheny-lenediamine, o-phenanthroline or 2,2′-dipyridyl; BBB = tridentate ligand (the Schiff base derived from benzoylhydrazide and salicylaldehyde), have been synthesized and characterized by elemental analysis, molar conductance, molecular weight, i.r. spectra and magnetic susceptibility measurements. The principle of coordination number expansion of a six coordinate homochelate, [MoO2(H2O)(BBB)] was used to prepare the complexes, which are nonelectrolytes, monomers and diamagnetic. The i.r. spectral data reveal that they possess a cis-MoO2 structure. The νsym(OMoO) and νasym(OMoO) shifts and the difference between νsym(OMoO) and νasym(OMoO) have been related to an increase in electron density at the molybdenum atom therein. © 1985 VCH Verlagsgesellschaft mbH.