CHEMICAL BONDS AND ELECTRONIC STRUCTURES OF THE METHONIUM CATIONS ${\rm CH}_{6}^{2+}$ AND ${\rm CH}_{7}^{3+}$

Abstract

Six isomers with C2v, D3h, C5v, D2d, Oh, and C4vsymmetries of [Formula: see text] and two isomers with C3vand C2vsymmetries of [Formula: see text] are investigated at the high ab initio level combined with the natural bond orbital and the atoms-in-molecules theorems. The hyperconjugative interaction and the electron topological analyses indicate that the multiple three-center two-electron (3c-2e) hyperbond is the common chemical-bonding basis for [Formula: see text] and [Formula: see text] species. In contrast to the planar 3c-2e (triangle structure) and planar four-center four-electron (4c-4e) hyperbonds in [Formula: see text] isomeric species, the 3c-2e hyperbond in [Formula: see text] (C4v) is linear while the 4c-4e hyperbonds in [Formula: see text] (C5v, D2d, Oh) are unplanar. [Formula: see text] (C2v) and [Formula: see text] (C3v) as the global minima have many resonance structures predicted by the natural bond resonance theory, indicating the high possibility of the hydrogen scrambling which is similar to the scenario of [Formula: see text].