Ligand Hyperfine Interactions in Molybdenyl and Chromyl Halide Complexes

Abstract

Ligand superhyperfine interactions due to 35,37Cl and 19F have been observed in the ESR spectra of MoOCl5 2−, MoOF5 2− and CrOF5 2−. The presence of both isotropic and anisotropic ligand hyperfine splittings indicates considerable covalency in these complexes. The bonding coefficients, which have been calculated with resonable accuracy, reveal moderately strong in‐plane π bonding involving the metal d xy orbital and the ligand p y orbital. The spin–orbit interaction of the halide ligand is shown to be important in determining the g values. A configuration‐interaction treatment has been used to account for the spin densities in the ligand p x and s orbitals. The ESR spectra show that in solutions of KCrOF4 in aqueous hydrofluoric acid two species, CrOF4 − and CrOF5 2−, are present.