INTERMOLECULAR AND INTRAMOLECULAR 2-CENTER 3-ELECTRON BONDING IN RADICAL CATIONS OF ALKYL BROMIDES

The reaction of hydroxyl radicals with different alkyl bromides in aci dic aqueous solution has been studied by nanosecond pulse radiolysis t echnique at a high solute concentration where solute dimer radical cat ions are formed. The observed rate constant for the decay of dimer rad ical cations is deconvoluted to different processes and the deprotonat ion of the radical cation is found to be the rate determining step. Th e inter- and intra-molecular two-centre three-electron bond strength i s determined for a series of radical cations from alkyl bromides and d ibromoalkanes at a semi-empirical level with AM1 parametrization. Calc ulations indicate that the strengths of hemi-bond decreases as the len gth of methylene linkage increases in case of dimer radical cations.