The crystal-field energy levels of dibarium copper(II) formate tetrahydrate and copper(II) formate tetrahydrate

Abstract

In contrast to previous reports, the e.s.r. and polarised electronic spectrum of Ba₂Cu(HCO₂)₆·4H₂O show the presence of a small rhombic perturbation (α= 2·5°). The order of the one-electron orbital energies is d_x²–y² > d_z² > d_xy > d_xz > d_yz. The polarised spectrum of Cu(HCO₂)₂·4H₂O is very similar and leads to the same energy order, except that d_xz and d_yz are degenerate. From the g-factors and the electronic energies, values of the anisotropic spin-orbit reduction parameters are obtained which suggest that these coefficients are not only dependent upon electron delocalisation.