ESR spectra of low-symmetry high-spin cobalt(II) complexes. 3. Square-pyramidal nitratotetrakis(methyldiphenylarsine oxide)cobalt(II) nitrate

Nitratotetrakis(methyldipheny1arsine oxide)cobalt(II) nitrate has been described as a square-pyramidal complex with the cobalt ion in a C, site symmetry. Despite this, the observed g values are highly anisotropic; g, = 8.6, g2 = 1.3, and g3 = 0.9. The smallest g value is found to make an angle of 12 & 5' to the perpendicular to the basal plane. The anisotropic gvalues are justified by the off-axis position of the Co-0 bond. A completely symmetry independent ligand field model allowed us to rationalize the data in a simple and effective way.