Microwave spectrum and conformation of 6-thiabicyclo[3.1.0]hexane

The microwave spectrum of 6-thiabicyclo3.1.0]hexane (cyclopentene sulfide) has been measured in the region 26,500-40,000 MHz. The experimental data are consistent with a single stable conformation. Furthermore, these data can only be satisfactorily explained by assuming that this conformation is the boat form. Rotational constants were obtained, both for the ground state and two excited vibrational states, while centrifugal distortion coefficients were obtained for the ground state and one excited vibrational state. The ground state rotational constants found were A₀ = 5026.243 ± 0.003 MHz, B₀ = 2833.813 ± 0.003 MHz, and C₀ = 2411.679 ± 0.03 MHz. For the ground state of the molecule, the electric dipole moment components were found to be μ_a = 1.800 ± 0.012 D and μ_c = 1.155 ± 0.024 D, yielding a total dipole moment μ = 2.139 ± 0.027 D.