Single-crystal electron paramagnetic resonance of (dialkyldithiocarbamato-S,S′)[hydrotris(3,5-dimethylpyrazolyl)borato] oxovanadium(IV)(alkyl = ethyl or n-propyl)

Abstract
The single-crystal EPR spectra, at room temperature and Q-band frequencies, of [VO(L)(R2dtc)] diluted in the isostructural molybdenum compound are reported [L = hydrotris(3,5-dimethylpyrazolyl)borato, R2dtc = dialkyldithiocarbamato (R = Et or Prn)]. The relative orientations of the principal axes of the g and A tensors show small angles of non-coincidence. The relationships between the EPR parameters and the molecular geometries are considered. Of the eight possible interpretations of the single-crystal data for each compound, those which give the most consistent interpretation between the structurally similar molecules are: for R = Et, g11= 1.958, g22= 1.983, g33= 1.986, A11=–151.9 × 10–4 cm–1, A22=–53.0 × 10–4 cm–1, A33=–51.0 × 10–4 cm–1, with g11 and A11 at 15.8° and 12.9° from VO, respectively; R = Prn, g11= 1.956, g22= 1.982, g33= 1.985, A11=–153.4 × 10–4 cm–1, A22=–56.6 × 10–4 cm–1, A33=–48.7 × 10–4 cm–1, with g11 and A11 at 6.0° and 2.1° from VO, respectively. These EPR parameters and the molecular geometries, in conjunction with a parametrised angular overlap model, have been used to discuss the electronic structures of both molecules. A corresponding treatment of the literature data on [VO(Et2dtc)2] is also given for comparison.

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