The twohyphen;dimensional potential energy surface for the ring puckering and ring twisting of 1hyphen;silacyclopenthyphen;3hyphen;enehyphen;d0, 1hyphen;d1, and 1, 1hyphen;d2

摘要

The farhyphen;infrared spectra of 1hyphen;silacyclopenthyphen;3hyphen;ene and an isotopic mixture containing both 1hyphen;d1and 1, 1hyphen;d2species have been recorded and analyzed. In addition to the main ringhyphen;puckering series, a weak side band series, resulting from molecules in the ringhyphen;twisting excited state, was observed for the undeuterated molecule. In the 330ndash;520 cmminus;1region of the infrared spectrum of the isotopic mixture, combination bands of the puckering with the SiHD or SiD2rocking were observed. The ringhyphen;twisting fundamental was also assigned to the 380.6 cmminus;1band in this region. Analysis of the data for all three isotopic species results in the following twohyphen;dimensional potential energy surface:V(cmminus;1)=2.08times;105x41minus;0.005times;105x21+0.547times;105x22+1.70times;105x21x22wherex1andx2are the ringhyphen;puckering and ringhyphen;twisting coordinates (in Aring;), respectively. The potential minimum corresponds to a planar conformation and the positive cross term shows the vibrational interaction to be anticooperative.