Gaseous infrared spectra of the simplest geminal diol CH2(OH)2 and the isotopic analogues in the hydration of formaldehyde

Abstract

The infrared spectrum of the simplest geminal diol, methanediol or methylene glycol (CH₂(OH)₂), was successfully probed in the gaseous hydration of formaldehyde. The observed absorption bands coincided with the anharmonic vibrational wavenumbers predicted by B3LYP/aug-cc-pVTZ calculation. Based on the predicted rotational parameters and dipole derivatives, the simulated rovibrational contours of CH₂(OH)₂ agreed with the experimental spectrum, and the band origins of the OCO symmetric stretching mode (b-type) and the OCO asymmetric stretching mode (a-type) were determined to be 1027 and 1058 cm⁻¹, respectively. In addition, the isotopic analogues, CD₂(OH)₂, CH₂(OD)₂, and CD₂(OD)₂, were also investigated. The band origins of the CD₂ wagging mode (a-type) and the COH bending mode (a, c-type) of CD₂(OH)₂ were also determined to be 1121 and 1301 cm⁻¹, respectively. The successful infrared characterization of gaseous methanediol makes it possible to directly investigate the relevant chemical reactions of geminal diols in atmosphere, astrophysics, and water-mediated reactions.