Synthesis and Crystal Structure of Cobalt(III) Complexes of Salen Type Schiff Bases and Tertiary Phosphanes as Ligands

The new [Co(Salen)(PBu3)2]ClO4, [Co(Salen)(PBu3)2]BF4, [Co(Salpn)(PBu3)2]ClO4 and [Co(Salen)(PMe2Ph)2]ClO4 ( where salen = bis(salisylaldehyde)ethylenediimine)) complexes were synthesiszed and chracterized by IR, UV-Vis, 1H NMR spectroscopy and elemental analysis. The IR and 1H NMR spectra cofirmed that the synthesised complexes contain Schiff base ligand, phosphane and conter ion and the elemental analysis is in good agreement with those calculated for the proposed formula. The coordination geometry of [Co(Salen)(PMe2Ph)2]ClO4 and [Co(Salen)(PBu3)2]ClO4 complexes were determined by X-ray crystallography. It has been found that all the complexes are hexa coordinate in the solid state. Cobalt atom exhibits a distorted octahedral geometry and the salen ligand has the N2O2 coordinated environment in the equatorial plane. Cobalt complexes with ligands derived from salicylaldehyde have been well studied.[1] They are regarded as models for the Cobalamine (B12) coenzymes [2-4] classified as an oxygen carrier [5] and used as a catalyst for the preparative oxygenation of phenols [6] indols [7] and amines.[8]. The catalytic activity of Co(III) with salen complexes has been investigated. It was shown the catalytically active species contains cobalt in the Co(III) oxidation state [9-15].