ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The structures and stabilities of N2 and its 15 possible first-row isoelectronic analogs (CO, BF, BeNe, NO+, CF+, BNe+, O2+2, NF2+, CNe2+, OF3+, NNe3+, ONe4+, F4+2, FNe5+, and Ne6+2) have been examined using ab initio molecular orbital theory. Equilibrium structures have been obtained at a variety of levels of theory including MP3/6-311G(d) and ST4CCD/6-311+G(2df ) and dissociation energies determined at the MP4/6-311+G(3d2f ) level. Full potential energy curves for dissociation, including dissociation barriers, have been obtained at the CASSCF/6-311G(d) level. Spectroscopic constants have also been determined at this level. For the neutral and monocation analogs of N2, the calculated equilibrium geometries, dissociation energies, and spectroscopic constants are in good agreement with the experimental values. The dication analogs of N2, namely O2+2, NF2+, and CNe2+, are all found to be kinetically stable species lying in deep potential wells. In particular, the hitherto unobserved NF2+ dication is predicted to have a short equilibrium bond length (1.102 A(ring)) and a large barrier (445 kJ mol−1) to dissociation to N++F+. Thus NF2+ should be experimentally accessible in the gas phase. The (experimentally known) O2+2 dication is predicted to contain the shortest bond between any two heavy atoms, our best estimate of the bond length being 1.052 A(ring). The first excited state (A 3Σ+u) of O2+2 is predicted to be unbound, and observed metastable decomposition processes are reinterpreted in terms of the ground-state (X 1Σ+g) potential surface. In agreement with previous theoretical studies, we find that CNe2+ is a kinetically stable species, albeit with a relatively long C–Ne bond length. The OF3+ trication is calculated to have a relatively short bond but lies in a well of depth only 23 kJ mol−1. The potential energy curves of the other highly charged species are found to be purely repulsive.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.456967
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