EPR studies of a molybdenyl complex in single crystals of NH<inf>4</inf>Cl

Electron paramagnetic resonance of [MoOCl5]2- has been studied in single crystals of NH4Cl. At room temperature the interaction of the unpaired electron with both the even and odd isotopes of molybdenum has been observed. The existence of metal-halogen π bonding is established by the observation of the ligand superhyperfine interaction at liquid nitrogen temperatures. Various possible models corresponding to the different spatial configurations of the molybdenyl complex in the lattice are considered to explain the experimentally observed features. The spectra are analysed using the usual spin-hamiltonian corresponding to tetragonal symmetry. The spin-hamiltonian parameters obtained are: g∥ = 1.964, g- = 1.945, A∥ = 75.53 × 10-4 cm-1, A⊥ = 38.42 × 10-4 cm-1. © 1975.