Spectra and structure of smallhyphen;ring molecules. XLI. Microwave spectrum of 3hyphen;phospholene

摘要

The microwave spectra of 3hyphen;phospholene and 3hyphen;phospholenehyphen;1hyphen;d1were recorded from 12ndash;40 GHz and 26.5ndash;40 GHz, respectively. OnlyAhyphen;type transitions were observed. TheRbranch assignments have been made for the ground state of the hyphen;d1molecule, and the ground, first, and second excited states of the ringhyphen;puckering mode for the rsquo;rsquo;lightrsquo;rsquo; molecule. It is shown that the skeletal atoms of the fivehyphen;membered ring are noncoplanar and the ring is puckered by an angle of approximately 18deg;. Additionally, it is shown that the most stable form of the molecule is the rsquo;rsquo;endorsquo;rsquo; form with the Pndash;H bond directed toward the double bond. From relative intensity measurements it is concluded that the first excited state of the ringhyphen;puckering mode has a frequency of 160plusmn;15 cmminus;1. From measurements of the Stark effect for the 3hyphen;phospholene molecule the dipole moment components were determined to be Verbar;mgr;aVerbar;=1.10plusmn;0.02D, Verbar;mgr;bVerbar;=0.0D(assumed), and Verbar;mgr;cVerbar;=0.16plusmn;0.05Dwith the total dipole moment being Verbar;mgr;tVerbar;=1.11plusmn;0.02D. These results are compared to other similar molecules.