Abstract:

The unimolecular charge separations and neutral loss decompositions of the doubly charged ions [C_7H_7Cl]~(2+), [C_7H_6Cl]~(2+·) and [C_7H_5Cl]~(2+) produced in the ion source by 70 eV electron impact from 3 chloro-toluenes and benzyl chloride isomers were studied using MIKES. The isomerizations for these ions are prior to the decompositions, which make the MIKES for 4 isomers almost identical. The ejections of H depend on whether the parent ion is an odd-electron or an even-electron ion. The even-electron doubly charged ions can only decompose to even-electron fregments by loss of even-number of H atoms, and we called the phenomena as even-electron rule. The structures of the transition states for charge separations are usually different from the structures of neutral molecules. Several structures were discussed based on the values of the kinetic energy releases (T) during the charge separation processes.

Key words: [C7H7Cl]2+, [C7H6Cl]2+·, [C7H5Cl]2+, Charge separation, Unimolecular decomposition