Model study of the acid-base proton-transfer reaction of the ClP•••OH2 pair in low-polarity solvents

We present a theoretical study of a model of the ClH . . . OH(2)reversible arrow Cl-. . .(-) HOH24 acid-base proton-transfer reaction in nonaqueous solvents with low dielectric constants. Ln this low-polarity environment, both the reactants and products of the proton-transfer reaction are observable. The electronic structure of the acid-base pair is treated via a two-state valence-bond description parametrized using a combination of experimental and ab initio data. The fundamental nature of this proton-transfer reaction is investigated with particular emphasis on the effects of quantization of the proton and hydrogen-bond vibrations. Vibrational wave functions in these coordinates are presented, along with coordinate expectation values and variances, and are placed in the perspective of the proton-transfer process.