Crystal and molecular structure, electron spin resonance, and electronic spectrum of tetraphenylarsonium tetrachloro-oxomolybdenum(V)

Crystals of the title compound are tetragonal, space group P4/n, with a = 12.766(7), c = 7.785(5) Å, Z = 2. The crystal structure was solved by the heavy-atom method and refined by full-matrix least-squares calculations to R 0.050 over 735 statistically significant reflections from diffractrometer measurements. The square-pyramidal [MoOCl4]^- anion has 4mm (C4v) symmetrywith Mo-O 1.610(10), Mo-Cl 2.333(3) Å, O-Mo-Cl 105.2(1)°. The [AsPh4]⁺ cation has crystallographic 4 (S4) symmetry, with As-C 1.902(7) Å, and C-As-C angles of 105.3(3) and 111.6(3)°. The polarised single-crystal electronic spectra at room temperature and 5 K show that the first two bands at 15.4 and 22.5 kK are due to b2*(4dxy) → e*(4dxz,yz, Mo-Oπ*) and e(Mo-Oπ) → a1*(Mo- Oα*) excitation respectively. The single-crystal e.s.r. parameters (g∥ 1.967 ± 0.002, g⊥ 1.950 ± 0.002) and the Mo hyperfine parameters from solutions in CH 2Cl2 and solid [AsPh4] [NbOCl4], (Ā 47.9 × 10^-4 cm^-1, A∥ 72.8 × 10^-4 cm^-1), have been used in conjunction with the electronic spectrum to estimate the metal d-orbital contributions to the metal-ligand antibonding molecular orbitals.

Duke Scholars

Author Andrew T. McPhail Chemistry