Solvated electron pairing with earth alkaline metals in THF. 1. Formation and structure of the pair with divalent magnesium

The reactivity of a solvated electron with Mg I I salts in THF is investigated by pulse radiolysis. With magnesium chloride, no reaction is observed, but when magnesium perchlorate is used, the solvated electron reacts toform a species absorbing in the near-infrared. Conductivity measurements show that neither MgCl 2 nor Mg-(ClO 4 ) 2 is dissociated in THF. Quantum chemical calculations show that the difference in behavior between the two salts can be traced back to the electron affinities of the solutes in the gas phase. The solvated electron forms a stable pair only with magnesium perchlorate. The structure of this pair is proposed. The rate constants of the reactions and the extinction coefficients of the different species involved in the formation and decay of the pair are determined with a probabilistic global analysis method of the time-resolved absorbance signals.