Spectroscopic and Structural Characterization of Formazanyl Copper Complexes

Abstract

Abstract 1-(o-Substituted phenyl)-3,5-diphenyl-5-formazans form various kinds of complexes. The copper(II) complexes of 1,3,5-triphenyl-5-formazan and 1-(p-Cl and o-CH3)-3,5-diphenyl-5-formazans (Group I) showed about 0.012 cm−1 of the parallel component of the copper(II) ESR splitting constant; those of the copper(II) complexes of 1-(o-Cl and o-Br)phenyl-3,5-diphenyl-5-formazans (Group II) were 0.018 cm−1. The f-values in the near-infrared region of the former complexes were almost 10-times larger than those of the latter complexes. The difference was attributed to a tetrahedral distortion of about 65—70 degrees from the planar structure in Group I; the complexes of Group II, however, were almost planar. The complexes of 1-(o-OH and o-COOH)phenyl-3,5-diphenyl-5-formazans (Group III) showed exchange interactions between two copper(II) ions with exchange energies of −375 and +33.5 cm−1 for the former and the latter complexes of Group III, respectively. Referring to the exchange and dipolar interactions, the Cu–Cu distances and the Cu–O–Cu bridging angles are discussed.