A theoretical study of HArF, a newly observed neutral argon compound

Computational results up to the CCSD(T)/aug-cc-pV5Z level are presented as support for the newly observed argon containing compound, hydrido argonfluo ride (HArF). The molecule is calculated to be linear with R(H-Ar)=132.9 pm and R(Ar-F)=196.9 pm. The calculated vibrational frequencies, corrected for anharmonicity and matrix effects, are 462 (Ar-F stretch), 686 (bend) and 1 916 cm(-1) (Ar-H stretch). These are in good agreement with the correspondi ng experimentally observed frequencies of 435.7, 687.0, and 1969.5 cm(-1) f or the matrix isolated species [Nature 406, 874 (2000)]. Including correcti ons for the finite basis set as well as for the zero-point energy, the new molecule is stable by 0.15 eV compared to the dissociated atoms. HArF is fu rther stabilized by an additional barrier of 0.18 eV, arising from the avoi ded crossing between the states corresponding to the ionic (HArdelta+)(Fdel ta-) equilibrium structure and the covalent (HAr.)(F-.) dissociation limit. The dissociation of HArF via bending into the thermodynamic ground-state s ystem, consisting of Ar and HF, is protected by a 1.0 eV barrier. (C) 2001 American Institute of Physics.