The stereochemistry of oxovanadium(IV) complexes derived from salicylaldehyde and polymethylenediamines

Abstract

Several Schiff-base complexes of oxovanadium(IV), [VO{OC₆H₄CHN-CR¹R²(CH₂)_{n– 1}–NCHC₆H₄O}] where n= 2 (R¹ and R²= H or CH₃) and n= 3–10 (R¹= R²= H), have been isolated and their spectroscopic and magnetic properties have been investigated. The ν(VO) stretching vibration frequencies fall in the range 861–994 cm^–1. Minimum and maximum d_π–p_π overlaps in VO were observed in (4; R¹= R²= H, n= 3) and (7; R¹= R²= H, n= 6) respectively. The electronic spectra in chloroform and pyridine and in the solid state indicate the possibility of an inversion of the ordering of energies of the e_π* and b₁* levels; consequently a diversity of geometries were observed as the methylene chain length increased. The effective magnetic moments at room temperature of the complexes are between 1.64 and 1.81 B.M.; however, the θ values are relatively small.