The conformational landscape of 1,2-propanediol was investigated by quantum chemical calculations from
(1) F. J. Lovas, D. F. Plusquellic, B. H. Pate, J. L. Neill, M. T. Muckle, and A. J. Remijan, 2009, J. Mol. Spectrosc. 257, 82.
The aG'g conformer was found to be the lowest one with the gG'a conformer calculated to be 106 K higher in energy and the g'G'g conformer 165 K higher. The g'Gg conformer is the seventh one in energy, calculated to be 540 K above the lowest.
Several higher lying conformers of 1,2-propanediol were studied recently by
(2) O. Zakharenko, J.-B. Bossa, F. Lewen, S. Schlemmer, and H. S. P. Müller, 2017, J. Mol. Spectrosc. 333, 23.
This analysis also included data from (1).
As there are uncertainties concerning the exact energy differences among the conformers, we treat each conformer as isolated species.
According to (2), perturbations occur at higher J, so predictions should be viewed with some caution. Nevertheless, the predictions are expected to be sufficient for all astronomical observations. Predictions with uncertainties larger than 0.3 MHz should also be viewed with caution.
The dipole moment components are from a quantum chemical calculation from (1).