V, NB, AND TA HYDRIDE MOLECULES IN DEUTERIUM AND RARE-GAS MATRICES - INFRARED AND ELECTRON-SPIN-RESONANCE SPECTRA

The VH2 molecule was found to have S=3/2 and a 4Σ ground state with a zero-field splitting parameter |D|=0.315 cm-1. 51V (I=7/2) hyperfine splitting was observed in the ESR spectra, but the hydrogen hyperfine was unresolved. The narrowest lines were observed for VD2 in solid deuterium at ∼2 K. Efforts to observe VH4 via ESR were not successful presumably because it could not be prepared in a high enough concentration. The infrared spectra of NbH 2 molecules and their deuterated isotopomers were observed in solid deuterium and rare-gas matrices. NbH2 was found to be bent at 130°, in accord with theoretical calculations. NbH2 was not observed in ESR spectra although it presumably has a 4B1 ground state; this is attributed to a large (>4 cm-1) negative D value. NbH4 was observed via ESR as a tetragonally distorted (D 2d) tetrahedral molecule in its 2B1 lowest state resulting from a static Jahn-Teller effect. 93Nb (I=9/2) and also H hyperfine splittings were observed. A corresponding TaH4 spectrum was attributed to a similarly distorted tetrahedral S=1/2 molecule. © 1995 American Institute of Physics.