VCl4 Revisited:  ESR and Photolysis in Solid Hydrogen, Neon, and Argon; Formation of VH4

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2000-10, Vol.104 (41), p.9302-9306
• Main Authors: Graham, John T, Li, Weltner, W
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp0020079

Electron -spin-resonance (ESR) spectra of the VCl4 molecule were observed at low concentrations at 2−4 K in solid H2, D2, Ne, and Ar. As previously observed in other matrixes, the spectra of an axial molecule were obtained in H2, D2, and Ne, indicative of a Jahn−Teller (JT) distorted molecule with compressed tetrahedral D 2 d symmetry. However, in argon, a composite of an axial and a near-isotropic spectrum was observed, and annealing yielded only the isotropic at 4 K. This surprising result is discussed relative to JT dynamic vibronic interaction. Photolysis of VCl4 in H2 (and D2) matrixes yielded a new spectrum assigned to VH4 (or VD4), indicating that the tetrahydride is also a JT-distorted 2E ground-state molecule, in accord with earlier ab initio theory.