15min:

WEI LIN, ANDREA J. MINEI, ANDREW H. BROOKS, WALLACE C. PRINGLE AND STEWART E. NOVICK, Department of Chemistry, Wesleyan University, Middletown, CT 06459.

Rotational spectra of the neon cyclopentanone van der Waals complex were studied using a pulsed-jet Fabry-Perot Fourier transform microwave spectrometer. Spectra of the normal isotopomer along with those of five ¹³C, the ¹⁸O, and the ²²Ne substituted isotopomers were assigned in the frequency region of 6-23 GHz. The asymmetry of the neon location within the complex allows the observation of a, b, and c -type transitions. The rotational constants and centrifugal distortion constants for the parent isotopomer were determined to be A = 2728.8119(7), B = 1736.5880(5), and C = 1440.4682(5) MHz; and _J = 15.051(7), _JK = -13.96(4), _K = 49.97(5), _J = 3.603(3), and _K = 6.55(8) kHz. The coordinates of the neon in the principal axis system of C₅H₈O are a = 0.91, b = 0.78, and c = 3.26 Å, where the carbonyl bond lies along the a -axis and the oxygen position is a = 2.05 Å. Comparisons between the bonding and wide amplitude motions of the rare gases in the neon verses the argon cyclopentanone complexes will be discussed.