GAS-PHASE CONFORMATIONAL-ANALYSIS OF 1,4,7-TRITHIACYCLONONANE

Conformational analysis of 1,4,7-trithiacyclononane, [9]aneS(3), in th e gas phase was done using three techniques: ab initio molecular orbit al calculations at the HF and MP2 levels as well as microwave and phot oelectron spectroscopies. The photoelectron spectroscopic data show ev idence for at least two conformations with different ionization energi es. Using the calculated photoelectron spectra, the observed sulfur 3p ionization peaks can be assigned to C-1 and C-2 conformations. Forty of the observed microwave transitions can be assigned to a C-1 symmetr y, asymmetric top, rigid rotor spectrum with rotational constants A = 1155.651(3) MHz, B = 998.442(3) MHz, and C = 629.426(2) MHz. Additiona l microwave lines are believed to be due to a nonrigid C-2 symmetry co nformation. No significant populations of conformers of higher symmetr y are found.