Calculations and measurements for the rotational spectrum and structure of the cyclopentadienyl thallium – benzene complex

Calculations on the structure of the cyclopentadienyl thallium – benzene complex were made using Gaussian-G16 and Spartan programs. Calculations converged to symmetric top and asymmetric top structures. Rotational transition frequencies for the cyclopentadienyl thallium – benzene complex were measured in the 4.5–8.3 GHz range using a Flygare-Balle pulsed beam microwave spectrometer. The basic spectrum from the preliminary experiments exhibited splittings of the observed transitions which would not be expected for a rigid symmetric top molecule. 11 of the measured transitions were assigned to an asymmetric top structure and fit, yielding rotational constants A = 1136.8(11) B = 378.44(11) MHz and C = 375.173(79) MHz.