Showing papers by "Ming Wah Wong published in 1988"

Multiply-charged cations: remarkable structures and stabilities

Abstract: The use of ab initio molecular orbital theory with moderately large basis sets and incorporation of electron correlation to study multiply-charged ions is discussed. Despite extreme coulomb repulsion, several of the ions have very short bonds. The C-F lengths in HCF2+ (I. 1 I1 A) and HeCF3' (1.102 A) and the C-CI length in HCCI" (1.466 A) are the shortest known for these types of bonds. Some of the more highly charged ions which have been examined, including the HeCF3+ and CHe;'' trications and the CHe:' tetracation, are predicted to be observable species, despite the possibility of highly exothermic (by -1000 kJ mol-' and more) fragmentations. It is found that unrestricted Moller-Plesset perturbation theory is not a suitable procedure for examining the fragmentation of multiply-charged ions in cases where spin contamination is significant in the underlying unrestricted HartreeFock wavefunction. Transition structures for asymmetric fragmentations of multiply-charged ions often occur late on the reaction pathway, with the length of the breaking bond hvo or more times greater than its value in the corresponding equilibrium structures.