Synthesis and characterization of some metal(II) complexes of isomeric unsymmetrical Schiff bases and their adducts with triphenylphosphine

Abstract

We report the isolation of two unsymmetrical isomeric Schiff bases obtained from condensation of 2,4-pentanedione/1-phenyl-1,3-butanedione and 2-hydroxy-4-methoxyacetophenone/2-hydroxy-4-methoxybenzophenone with ethylenediamine and their VO(IV), Co(II), Ni(II), and Cu(II) complexes. Further reaction of each complex with triphenylphosphine resulted in formation of 1 : 1 adducts, with water occupying the sixth position in some, except copper and cobalt formed 1 : 2 adducts with [ML¹]. The purities of the ligands and complexes were established by microanalyses and the complexes were characterized by magnetic susceptibility, conductance, infrared and electronic spectral measurements. The involvement of the azomethine N and phenolic O in bonding resulted in an N₂O₂ chromophore around the central metal atom. Infrared and electronic spectral data are consistent with square-planar/tetrahedral geometry for Ni(II), Co(II), and Cu(II) complexes and a five-coordinate, square-pyramidal geometry for the VO(IV) complexes. Evidence for triphenylphosphine adducts is adduced from microanalyses, spectral changes, and magnetic susceptibility measurements.

Keywords:

• Adducts
• Unsymmetrical Schiff base
• Triphenylphosphine
• Metal(II)

Acknowledgments

The authors thank South African Bureau of Standards and Dipartmento di Scienze Chimiche, Universita di Trieste, Italy. GAK also acknowledges financial support from National Research Foundation (South Africa) and the Royal Society (UK).