Raman, infrared, and microwave spectra and conformational preferences of meso-Bisoxirane

Vibrational infrared and Raman spectra of liquid and solid meso-bisoxirane and infrared spectra of the gaseous phase were recorded. Additionally, micr owave rotational spectra from 40 to 18 GHz were recorded. The vibrational s pectra demonstrate the presence of two conformations in the fluid phases bu t only one in the solid state. Infrared and Raman activities and gasphase b and contours indicate that the trans conformer with C-i molecular symmetry is more stable than the gauche conformer (C-1 symmetry). Variable temperatu re studies of two pairs of Raman lines are consistent with a Delta H value of 0.31 +/- 0.10 kcal/mol in the liquid state, Rotational constants (A = 91 87.45 +/- 0.04, B = 2651.80 +/- 0.01, C = 2608.92 +/- 0.01 MHz) and the dip ole moment (mu(total) = 3.03 D) were determined for the gauche conformer. M odel calculations give an acceptable match to the observed rotational const ants for an H-C-C'-H' dihedral angle of 60 degrees. The relationship of mes o-bisoxirane to other similar three-membered ring compounds is discussed. P ublished by Elsevier Science B.V.