Abstract
Low-temperature powder ESR studies of Cu(sal)
2·4H
2O, Cu(sal)
2(2-pycar)
2 and Cu(sal)
2(3-pycar)
2 (sal = salicylate ion, pycar = pyridylcarbinol) are reported. Spin-Hamiltonian parameters (obtained from experimental spectra, by the nonlinear optimization method) indicate, that the unpaired electron is in the antibonding ψ
b
1g
molecular orbital in all complexes, which clearly demonstrates an elongated tetragonal bipyramidal coordination around Cu(II). Spin-Hamiltonian parameters are used to estimate the molecular orbital coefficients for the Cu(sal)
2(2-pycar)
2 and Cu(sal)
2(3-pycar)
2.