Polymer complexes: 25. Complexing ability of poly(5-vinylsalicylidene-2-aminopyridine) towards different metal( ii) salts

Abstract

Mononuclear and binuclear complexes of poly(5-vinylsalicylidene-2-aminopyridine) † † Systematic name: poly[2-(5-vinylsalicylidenimino)pyridine] were prepared by the reaction of the homopolymer with copper( ii), cobalt( ii), nickel( ii), cadmium( ii), dioxouranium( vi) and palladium( ii) salts. Metal( ii) acetates and palladium chloride were found to give mononuclear complexes, while cupric chloride gave a binuclear complex. The polymer complexes have been characterized on the basis of elemental analysis, u.v. and i.r. spectroscopy, and magnetic susceptibility measurements. The stereochemistry and the nature of the complexes are markedly dependent upon the molar ratios of the reactants, the pH of the system and the nature of the anions involved. In all of the complexes the homopolymer was chelated to the metal ion through the nitrogen atom of the azomethine group and the oxygen atom of the phenolic group. The low value of the magnetic moment of the binuclear copper complex is due to an antiferromagnetic interaction between two adjacent copper atoms. The ligand field parameters have been calculated and related to the electronic environments. The electronic absorption of the homopolymer was investigated in organic solvents of varying polarities and buffer solutions of different pH, and the behaviour in the latter has been utilized in calculating the p K a of the phenol group.