Ligand hyperfine interactions in oxyhalides of pentavalent chromium, molybdenum and tungsten II

The electron paramagnetic resonance (EPR) spectra of the ions CrOF5=, MoOF5=, WOF5=, MoOCl5=, MoOBr5=, WOCl5= and WOBr5=, all incorporated into a single crystal of a suitably chosen host lattice, are presented. An attempt is made to correlate the EPR parameters to bonding orbital coefficients by using the Abragam and Pryce method. The analysis of the ligand hyperfine tensor components in bonding coefficients gives satisfactory results for the oxyfluorides with an increase in orbital delocalisation going from chromium to molybdenum. The existing methods of correlating g‐ and A‐tensor to molecular orbital coefficients are reviewed critically and shown to be highly dependent on an arbitrary choice of a charge distribution over the complex.