The formamidine–formic acid dimer: a theoretical examination of its equilibrium structure and of the double-proton-transfer process

Abstract

Ab initio molecular-orbital calculations with moderately-sized basis sets and incorporating electron correlation predict that the formamidine–formic acid dimer has a doubly-hydrogen-bonded equilibrium structure of C₁ symmetry and that double-proton transfer takes place via an ion-pair structure of C_2v symmetry in a stepwise process.