Planar Quadri-co-ordinate Complexes of Cobalt(II) with Schiff Bases Derived from Salicylaldehyde

In order to establish the electronic absorption spectra of quadri-co-ordinate, square-planar cobalt(II)-complexes, the absorption spectra of bis(salicylaldehyde)ethylenediiminato- and bis-(salicylaldehyde)propylenediiminato-cobalt(II) in solution have been determined, with the utmost care taken to avoid undesirable oxidation of the complexes. These compounds show characteristic ligand field band, with a comparatively sharp peak in the near-infrared region. Bis(salicylaldehyde)-α-α′-dimethylethylenediiminato- and bis(salicylaldehyde)-α,α′-diphenylethylenediiminato-cobalt(II) have deen prepared, and their spectra examined. These also show characteristic ligand field bands, with a sharp peak in the near-infrared region. Bis(salicylaldoximato)- and bis(salicylaldiminato)-cobalt(II) have been prepared, and their spectra examined. On the basis of the results obtained above, it has been concluded that these two complexes take a quadri-co-ordinate, planar configuration.