Conformational transformations of sulfur-containing rings: 2-methyltetrahydrothiophene gas-phase structures.
Stable conformations of five-member rings with the prototype cyclopentane are well-known to exist as twist or envelope structures and are of general interest in chemistry. Here, we report on the conformational analysis of the sulfur-containing ring 2-methyltetrahydrothiophene studied by a combination of molecular beam Fourier transform microwave (MB-FTMW) spectroscopy and quantum chemistry. Two twist conformers were observed, whereby highly accurate molecular parameters could be determined. In addition, the (34) S-isotopologue of the most stable conformer was assigned in natural abundances. Geometry optimizations were performed at different levels of theory and the calculated rotational constants were compared with experimental values. Two transition states optimized at the MP2/6-311++G(d,p) level using the Berny algorithm could illustrate the intramolecular conversion between both conformers.
Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen (Germany).
Vinh
V
Van
Christina
C
Dindic
Ha Vinh Lam
HV
Nguyen
Wolfgang
W
Stahl
ab initio calculation; configuration determination; conformation analysis; microwave spectroscopy; thiophene