Quantum Chemical Analysis of the Conformers, Fundamental Vibrational Frequencies, and Spectroscopic Constants of Methanetriol

The recent synthesis of methanetriol [CH(OH)3] under simulated interstellar conditions implies that this molecule may be present in various astronomical environments. This explicitly correlated coupled cluster theory study highlights that of the three conformers, the lowest-energy C1 form is polar enough (1.51 D) and exhibits unique enough rotational constants predicted in this work such that its observation is possible. Furthermore, the IR spectrum of the next-highest-energy conformer, Cs, will likely overlap with that of the C1 for its unique molecular vibrations, but the highest-energy C3 conformer may be distinguishable in the IR, especially for its C-H stretch at 2889.2 cm-1. All three conformers exhibit strong C-O stretching features around 1000 cm-1 and notable hydride bends between 1400 cm-1 and 1500 cm-1. Sterics appear to be stronger factors than the intramolecular hydride stretches in terms of the relative energies for the three conformers, and hybrid quartic force fields treat the low frequency fundamentals more reliably than pure, composite methods.