Crystal and molecular structure and electron spin resonance spectrum of trichloro-oxobis(triphenylphosphine oxide)molybdenum(v)

Monoclinic crystals of the title complex belong to space group P21/c, and have unit-cell dimensions of a = 18.977(5), b = 16.860(5), c = 22.099(6) Å, β = 96.50(5), and Z = 8. The crystal structure has been solved by direct methods using 3 286 statistically significant reflections from diffractometer measurements. Atomic parameters have been refined by full-matrix least-squares calculations to R 0.067. One of the two crystallo-graphically independent [MoOCl3(PPh3O)2] molecules in the asymmetric unit is disordered over two orientations. Bond lengths at the octahedrally co-ordinated molybdenum atom in the ordered complex molecule are: MO-O 1.662(13), Mo-O(PPh3O) 2.136(11) (trans to MO-O), 2.065(10) (trans to Mo-Cl), and Mo-Cl 2.348(5)-2.386(5) Å. Single-crystal e.s.r. spectra at room temperature give the following molecular values: g1 = 1.929 ± 0.002, g2 = 1.935 ±; 0.002, and g3 = 1.950 ± 0.002. The orientations of these values are different to those found for [MoOCl3{P(NMe2)3O}2] in that g3 is closest to the Cl-MO-Cl direction in [MoOCl3(PPh3O)2], whereas g2 is closest to this direction in [MoOCl3{P(NMe2)3O}2], The molecular g tensors for these two systems are compared qualitatively on the basis of the ligand-field strengths of the various ligands concerned.

Duke Scholars

Author Andrew T. McPhail Chemistry