ENDOR STUDIES OF [N,N'-ETHYLENEBIS(SALICYLIDENIMINATO)]COPPER(II) IN [N,N'-ETHYLENEBIS(SALICYLIDENIMINATO)]NICKEL(II) SINGLE-CRYSTALS

ENDOR spectra of [N, N-ethylenebis(salicylideniminato)]copper(II) doped in [N, N-ethylenebis(salicylideniminato)]nickel(II) single crystals are reported. Nitrogen hyperfine couplings, eight proton hyperfine couplings within the molecule, and five proton hyperfine couplings due to the neighboring molecules were determined. The quadrupole coupling tensor of the nitrogen nuclei was also obtained. From comparison with ligand hyperfine interactions for related copper(II) complexes, it is shown that the Cu-N bonds in [N, N-ethylenebis(salicylideniminato)]copper(II) have a stronger covalency than that of copper(II) complexes with a trans N-Cu-N configuration, while Cu-O in the former has less covalency than in the latter complexes. The presence of a correlation between the orbital hybridization of the coordinating atoms and spin distribution in the ligands is also suggested. The electron populations on the nitrogen orbitals were evaluated from the quadrupole coupling tensor. © 1979, American Chemical Society. All rights reserved.