PROPERTIES AND REACTIVITY IN GROUPS OF THE PERIODIC SYSTEM - ION-MOLECULE REACTIONS CH3X-DOT (X = F THROUGH AT)(CH3X+CENTER)

The reactions indicated in the title have been studied in terms of dir ect processes and complex formation. Quantum-chemical methods have bee n applied to the passage of an acid (H+, CH3+, X+) from CH3X+ to CH3X, and the abstraction of a radical (H-., CH3.,X-.) from CH3X by CH3X+.. It has been shown that a complex represented by a dimer of a methyl-h alide radical cation, (CH3X)(2)(+.), with a two-center three-electron bond X-X, has fairly high stability. These investigations were based o n non-empirical quantum-chemical calculations, the results being syste matically compared with experimental determinations. Some calculations included all electrons (X = F, Cl, Br), others were based on relativi stic pseudopotentials (X=F through At). The two sets of calculations a gree qualitatively with each other and with experimental observations.