MAHDI KAMAEE, MING SUN AND JENNIFER VAN WIJNGAARDEN, Department of Chemistry, University of Manitoba, Winnipeg MB R3T 2N2 Canada.
Chirped pulse Fourier transform microwave (FTMW) spectra of the van der Waals complexes of 2-fluoropyridine and 3-fluoropyridine with argon were serendipitously observed from 8-18 GHz while studying the pyridine monomers in 2011. These initial observations were used as a guide to measure the spectra of the complexes between 4 and 26 GHz using our Balle-Flygare FTMW instrument. With the higher resolution instrument, the 14N quadrupole hyperfine structure was observed and analyzed. Based on our ab initio calculations (MP2/6-311++G(2d 2p)), the observed rotational spectra are consistent with a geometry such that the argon atom lies over the plane of pyridine within several degrees of the c-axis of the ring. The center of mass separation between the two moieties is between 3.5 and 3.6 Å.