Tautomerization and dissociation of ethylene phosphonate ions [OCH2CH2O]P(H)O+: an experimental and CBS-QB3 computational study

The unimolecular gas-phase chemistry of the cyclic title ion, [OCH2CH2O]P(H)O+, 1a+, and its tautomer ethylene phosphite, [OCH2CH2O]POH+, 1b+, was investigated using mass spectrometry-based experiments in conjunction with isotopic labelling and computational quantum chemistry, at the CBS-QB3 level of theory. A facile tautomerization of the “keto” ion 1a+ into its more stable (by 34kcal/mol) “enol” isomer 1b+ is prevented by a substantial …