Systematic Variation of the Magnetic Hyperfine and Electric Quadrupole Interactions in Cu²⁺ Compounds; Covalent Effect

Abstract

NMR of copper nuclei belonging to the Cu 2+ ions in several magnetically ordered compounds have been investigated. The magnitudes of both hyperfine field and quadrupole splitting distribute in wide range and depend on the ligand ions. The calculated values based on ionic model are always large compared with the observed ones. Reasonable values are obtained when appropriate covalent effects are taken into account. The large quadrupole interaction arising from the non-cubic charge distribution of the ground state 3d electrons of the Cu ions is considerably cancelled out by the opposite contribution caused by the charges of the ligand ions.