Magnetic and spectral studies on tungsten(V) chloride and bromide and several oxyhalide and halide complexes of molybdenum(V) and tungsten(V)

Abstract

The electronic spectra, and magnetic susceptibility measurements in the temperature range 80–300°K, are reported for tungsten(V) chloride and bromide. These data are also presented for a number of molybdenum and tungsten(V) oxyhalide complexes of the types [MOX₅]^2– and [MOX₄]^– and halide complexes MX₆^–. Some infrared and conductivity data are also reported. The species studied all have the d¹ configuration, and values for 10Dq are derived from the spectra. The magnetic properties have been used to obtain estimates of the splitting of the ²T_2g ground term due to ligand field components of lower symmetry, the spin–orbit coupling constant, and an orbital reduction factor. Term splittings of up to 2000 cm.^–1, and substantial reductions in the free-ion spin–orbit coupling constant were observed. Existing spectral data have been extended to cover a wider wavelength range, and to provide extinction coefficients where possible. The suggested trimeric structure for the tungsten pentahalides is probably incorrect.