Measures of Covalency in Transition-Metal Chlorides

Abstract

The bonding between transition-metal ions and chlorine is largely ionic. It has been known that the small degree of covalency in transition-metal chloride crystals could be measured by transferred magnetic hyperfine interactions with the chlorine nuclei. Here we show that the Townes and Dailey theory allows one to derive the degree of covalency from the chlorine nuclear quadrupole coupling in these crystals. In the few cases where both magnetic hyperfine interactions and electric quadrupole interactions have been measured at the same nucleus, the degree of covalency calculated by the two methods agrees rather well. Both kinds of experiment indicate the importance of π bonding with the d orbitals as well as σ bonding.