THE EPR SPECTRA OF TETRADENTATE SCHIFF BASE COMPLEXES OF COPPER (II) II. N, N'-bis(salicylidene)ethylenediimine and 7-methyl-N, N'-bis (salicylidene)ethylenediimine

Abstract

Abstract The EPR spectra of single crystals of 63Cu(II) doped N, N'-bis(salicylidene)ethylenediimine Ni(II), [Ni(sal)2en] and 7-methyl-N, N'-bis(salicylidene)ethylenediimine Ni(II), [Ni(7-me sal)2en] have been studied. The usual doublet spin-Hamiltonian parameters for the complexes have been found to be: Cu(II)[(sal)2en]; g z =2.192 ± 0.002; g x =2.046 ± 0.004; g y =2.049 ± 0.004; A z =201.0 × 10−4 cm−1; A x =29.3 × 10−4 cm−1; A y =31.3 × 10−4 cm−1; AN z =12.6 × 10−4 cm−1; A N x =14.5 × 10−4 cm−1; A N y =15.7 × 10−4 cm−1; A H z =6.3 × 10−4 cm−1; A H x =7.3 × 10−4 cm−1; A H y =7.9 × 10−4 cm−1; Cu(II)[(7-me sal)2en]; g z =2.189 ± 0.002; g x =2.037 ± 0.004; g y =2.046 ± 0.004; A z =203.0 × 10−4 cm−1; A x =36.9 × 10−4 cm−1; A y =22.7 × 10−4 cm−1; A N z =12.6 × 10−4 cm−1; A N x =13.3 × 10−4 cm−1; A N y =14.0 × 10−4 cm−1. Values of molecular orbital coefficients calculated for these complexes show that their bonding properties are similar to those of other compounds of this type. There is considerable covalency in the metal-ligand [sgrave]-bonds, and significant in-plane pi-bonding is present.