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Observed bands in Raman and infrared spectra of 1, 3- dioxolane and their assignments

We present a Raman study of liquid and polycrystalline dioxolane, together with data for a solid dioxolane/argon film. Observed bands are assigned to the bent conformer on the basis of ab initio calculated vibrations, accompanied with potential energy distribution. Two internal modes were calculated at 658 and 720 cm-1 for the bent form. These were observed at 665 and 722 cm-1 in liquid, and split into four bands (at 694, 697, 725, and 728 cm-1) in the crystal at 10 K. In the solid dioxolane/argon film an additional band appears at 705 cm-1 (between the bands at 675 and 726 cm-1). A search for an additional dioxolane conformer trapped in argon was undertaken, by performing molecular dynamics simulations of dioxolane/argon solid film and averaging over all molecular conformations. The resulting conformation did not correspond to an energy minimum, but indicated that changes of only a few degrees in dihedral angles could shift ring deformation and O-C-O bending modes for more than 10 cm-1. Differential scanning calorimetric measurements gave evidence of solidification upon cooling at 146 K, and two phase changes on heating (one at 158.3 K, and a melting transition at 180.3 K). Further study is required on the hysteresis effect in the temperature behavior of dioxolane, and on the nature of the intermediate solid phase.

dioxolane; dioxolane/argon solid film; vibrational assignment; Raman; infrared; crystal; pseudorotation

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