Synthesis and structural studies on oxovanadium(IV) complexes with polyaza macrocyclic ligands derived from 1,4-phenylenediamine, formaldehyde and primary diamines

A new series of N₄ donor macrocyclic oxovanadium(IV) complexes of type [VO(mac)]SO₄ (mac = macrocyclic ligands derived from 1,4-phenylenediamine, formaldehyde and various primary diamines) have been prepared by template method. Tentative structures of the complexes have been proposed on the basis of elemental analyses, electrical conductance, magnetic moment and spectral (IR, electronic and EPR) data. The X-band EPR spectra of all the complexes have been recorded at room temperature and at liquid nitrogen temperature. The room temperature EPR spectra do not show anisotropy because of rapid tumbling of molecules in solution. The spectral studies support square-pyramidal geometry for the oxovanadium(IV) complexes.