Structural characterization of new fungicidal material; complexes of copper(II) with cyclic phosphazenes

Abstract

Hexaethylamino- and hexabenzylamino- derivatives of cyclotriphosphazene were prepared by substituting the chlorine atoms of hexachlorocyclotriphosphazene. A number of addition complexes of copper(II) acetate were then prepared with these cyclophosphazene ligands in different stoichiometric ratios. The complexes have been characterized on the basis of analytical and physico — chemical studies. The molar conductance measurements suggest the complexes are non - electrolytes. Infrared spectra indicate the coordination of phosphazene ring nitrogen to the copper but copper(II) acetate dimer was found intact after the complex formation. Electronic spectra suggest a distorted octahedral geometry around copper(II) ion. Room temperature magnetic moment values are lower than the spin — only values for d 9 system with one unpaired electron which suggests the possibility of weak antiferromagnetic coupling between two unpaired electrons present on the two Cu 2+ ions in the dimer. The plausible structures of the complexes have been suggested on the basis of molecular weight determinations. The fungicidal activities of the cyclophosphazene ligands and their Cu(II) derivatives were obtained against the fungi Aspergillus flavus and Aspergillus niger. It was found that the fungicidal activities of Cu(II) derivatives of cyclophosphazene ligands have been considerably enhanced compared to the ligands.