Electron-spin transfer due to covalent bonding in the (CrF 6 ) 3- group of K 2 NaCrF 6

Abstract

The magnetic moment density in the cubic compound K 2 NaCrF 6 has been measured by polarized neutron diffraction. Since the orbital moment in the chromium ions is quenched, and since the crystal contains non-overlapping (CrF 6 ) 3¯ ions, it is possible to interpret the data as the unpaired spin density of isolated clusters. A simple molecular orbital model of the cluster is used, with one adjustable covalency parameter A π . This model, although it predicts the qualitative features of the observed deviations from free Cr 3¯ ion behaviour, is not good enough to fit the intensities of all the reflexions. A Hartree-Fock calculation, of the type recently carried out on the octahedral (NiF 6 ) 4¯ cluster, is needed but has not been attempted here.