VIBRATIONAL SPECTRA AND STRUCTURE OF 4-MEMBERED RING MOLECULES .14. VIBRATIONAL ANALYSIS AND RING PUCKERING VIBRATION OF TRIMETHYLENE SELENIDE AND TRIMETHYLENE SELENIDE-D4

The infrared and Raman spectra of trimethylene selenide (TMSe) and trimethylene selenide 2,2,4,4 d4 (TMSe d4) have been recorded from 4000 to 15 cmâ1 in gaseous, liquid, and solid states. A vibrational assignment of the fundamentals is consistent with the expected Cs equilibrium configuration. A series of sharp bands associated with the ring puckering vibration have been observed in the mid and far infrared regions. The frequencies of the transitions have been employed in determining the following double minimum potential, barrier to ring inversion, and the equilibrium separation of the ring diagonal, 2x in angstroms, for TMSe, respectively: V(cmâ1 = 4.258 (± 0.02) à 105x4 â 2.5391 (± 0.007) à 104x2; 378.1 ± 4 cmâ1; 0.35 Ã. For TMSe d4 these quantities are: V(cmâ1) = 3.242(± 0.1) à 105x4 â 2.208 (± 0.033) à 104x2; 375 ± 10 cmâ1; 0.37 Ã, respectively. The dihedral angle of both molecules is calculated to be 32.5 ± 2°. © 1969, American Institute of Physics. All rights reserved.