Co(II), Ni(II) and Cu(II) complexes of some bifunctional arylidene-o-phenylenediamineSchiff bases have been prepared. Formation, stoichiometry and stability of the complexes have been tested in solution using electronic spectral measurements. Characterization of the complexes has been accomplished primarily by elemental analysis, molar conductance as well as electronic and IR spectral measurements. It is concluded that theo,o-hydroxy derivative (L 1) acts as a bivalent ONNO tetradentate ligand while the molecules of the other derivatives (L 2-L 5) are coordinated to the metal ions as bidentate NN ligands. The Cu(II)-L 1 complex is suggested to possess a tetrahedral geometry whereas the other complexes are suggested to exhibit a distarted octahedral geometry. The different bands observed in the electronic spectra of the complexes inDMF solutions have been assigned to the -*,L M CT and d-d electronic transitions.

Co(II), Ni(II) and Cu(II) complexes of some bifunctional arylidene-o-phenylenediamineSchiff bases have been prepared. Formation, stoichiometry and stability of the complexes have been tested in solution using electronic spectral measurements. Characterization of the complexes has been accomplished primarily by elemental analysis, molar conductance as well as electronic and IR spectral measurements. It is concluded that theo,o-hydroxy derivative (L 1) acts as a bivalent ONNO tetradentate ligand while the molecules of the other derivatives (L 2-L 5) are coordinated to the metal ions as bidentate NN ligands. The Cu(II)-L 1 complex is suggested to possess a tetrahedral geometry whereas the other complexes are suggested to exhibit a distarted octahedral geometry. The different bands observed in the electronic spectra of the complexes inDMF solutions have been assigned to the -*,L M CT and d-d electronic transitions.

The low excitation energy band appeared in the electronic spectra of some 4-hydroxyazobenzene derivatives is assigned to an electronic transition of the type n—π*. It is concluded that 4-hydroxyazobenzene derivatives exist mainly in the true azo form. On the other hand, the visible spectra of the azo compound; 4-hydroxy-2-carboxyazobenzene is interpreted on the basis that this compound exists in a tautomeric equilibrium of the type azo hydrazone, originating from the carboxyl group at the ortho position to the azo one.