Rotational spectra of high energy isomers, weakly bound complexes, and unstable molecules made in situ

The Fourier transform microwave spectra of high energy isomers, weakly bound complexes, and unstable molecules made in situ are the focus of this thesis.;High energy polar conformers of (OCS)2 and (N2O) 2 were observed. These polar dimers are of particular interest and have been the subject of much contention for decades. The long sought after polar isomers of these dimers have been observed using helium as the carrier gas and very high stagnation pressures offering a way to populate the higher energy conformer of these dimers. The rotational spectra of the linear Ar Cl 2 dimer and the gauche conformer of 1,3-butadiene were also attempted using helium as the backing gas but the searches were unsuccessful. These results are presented in Chapter 4.;Weakly bound complexes between rare gases neon and argon with five-membered rings displayed interesting results in terms of their binding sites. In all of the complexes presented in this thesis (argon cyclopentene oxide, neon cyclopentanone, argon methylene cyclopentane, and neon methylene cyclopentane), the rare gas behaves in a Lewis base fashion by preferentially binding to the most positive atoms of the ring and thereby avoiding contact with the negative atoms. Also of interest is the position of the rare gas in the principal axis system of the five-membered ring, which after studying many complexes in this series a conclusion can be drawn that if the rare gas atom is greater than 0.5 A off to the side of the center of mass along the b-axis, then the symmetry of the five-membered ring is different in the complex as opposed to the symmetry of the monomer. These results are presented in Chapter 5.;Lastly, structures of previously unknown unstable molecules have been determined. These molecules include H2PCCCN, which is of astronomical interest, and H(D)GeBr, which is of importance as a reactive intermediate in a variety of chemical processes. The rotational spectrum of CF3O was searched for, as fiuoroalkoxy radicals are common products of hydrofluorocarbon atmospheric oxidation This project in particular is still in its early stages and further analysis must be performed. These results are presented in Chapter 6.