Vibrational Spectra and Structure of Fourhyphen;Membered Ring Molecules. XIV. Vibrational Analysis and Ring Puckering Vibration of Trimethylene Selenide and Trimethylene Selenidehyphen;d4

摘要

The infrared and Raman spectra of trimethylene selenide (TMSe) and trimethylene selenidehyphen;2,2,4,4hyphen;d4(TMSehyphen;d4) have been recorded from 4000 to 15 cmminus;1in gaseous, liquid, and solid states. A vibrational assignment of the fundamentals is consistent with the expectedCsequilibrium configuration. A series of sharp bands associated with the ring puckering vibration have been observed in the midhyphen; and farhyphen;infrared regions. The frequencies of the transitions have been employed in determining the following doublehyphen;minimum potential, barrierhyphen;tohyphen;ring inversion, and the equilibrium separation of the ring diagonal,2xin angstroms, for TMSe, respectively:Vlpar;cmminus;1thinsp;equals;thinsp;4.258 lpar;plusmn;thinsp;0.02rpar;thinsp;times;thinsp;105x4thinsp;minus;thinsp;2.5391 lpar;plusmn;thinsp;0.007rpar;thinsp;times;thinsp;104x2; 378.1thinsp;plusmn;thinsp;4 cmminus;1; 0.35 Aring;. For TMSehyphen;d4these quantities are:Vlpar;cmminus;1rpar;thinsp;equals;thinsp;3.242lpar;plusmn;thinsp;0.1rpar;thinsp;times;thinsp;105x4thinsp;minus;thinsp;2.208 lpar;plusmn;thinsp;0.033rpar;thinsp;times;thinsp;104x2; 375thinsp;plusmn;thinsp;10cmminus;1; 0.37 Aring;, respectively. The dihedral angle of both molecules is calculated to be 32.5thinsp;plusmn;thinsp;2deg;.