The isomerization of [H2O-C=O]•+ and [HC(=O)OH]•+ into [HO-C-OH]•+:: proton-transport catalysis by CO

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)(.-) + H2O --> H2O-CO.- (3), followed by the CO catalyzed isomerization: 3 + CO --> 2 + CO. Solitary ions I and 2 do not interconvert, but theory and experiment agree that CO also efficiently catalyzes the conversion I --> 2. (C) 2004 Elsevier B.V. All rights reserved.