The isomerization of [H 2O–CO] [rad]+ and [HC(O)OH] [rad]+ into [HO–C–OH] [rad]+ : proton-transport catalysis by CO

Abstract

Mass spectrometry based experiments show that the m/ z 46 ion generated in chemical ionization experiments of CO with a trace of water is not the previously proposed formic acid ion, HC(O)OH + ( 1). Instead, the more stable dihydroxycarbene ion, HO–C–OH + ( 2) is formed. A mechanistic analysis using the CBS-QB3 model chemistry supports the reaction sequence: (CO) 2 + + H 2O → H 2O–CO + ( 3), followed by the CO catalyzed isomerization: 3 + CO → 2 + CO. Solitary ions 1 and 2 do not interconvert, but theory and experiment agree that CO also efficiently catalyzes the conversion 1 → 2.