The water-solvated methanol ion and its isomers: experiment and theory

• Published in: International journal of mass spectrometry Vol. 222; no. 1; pp. 41 - 48
• Main Authors: Cao, Jie, Tu, Ya-Ping, Sun, Weixing, Holmes, John L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2003
• Subjects: Dissociation mass spectra; Metastable ion; Tandem mass spectrometry; Tandem mass spectrometry; Dissociation mass spectra; Metastable ion
• ISSN: 1387-3806; 1873-2798
• DOI: 10.1016/S1387-3806(02)00949-1

Tandem mass spectrometry combined with ab initio calculations was used to explore the chemistry of the water-solvated methanol cation and its isomers, including the distonic methanol ion solvated by water, CH 2OH 2 +/H 2O ( I), the methanol molecular ion associated with water, CH 3OH +/H 2O ( II), and protonated methanol bound with a hydroxyl radical, CH 3OH 2 +/HO ( IV). Another ion, [H 2O⋯HCH 2OH +] ( III), where the water molecule is attached to a methyl H of the methanol cation, proved inaccessible experimentally although it was predicted to be stable in a shallow potential well by theoretical calculations. The ions were generated by collision-induced loss of a radical or atom from appropriate proton bound molecular pairs. The heats of formation of ions ( I) to ( IV) were calculated to be 448, 482, 486 and 538 kJ/mol, respectively. Ions ( I), ( II) and ( IV) can be identified by their metastable ion and collision-induced dissociation mass spectra. A partial potential energy surface linking the isomers is used to discuss the experimental data obtained with deuterium-labeled species.