COMPARISON OF SPECTROSCOPIC AND AB INITIO STRUCTURES FOR THE HYDROGEN-BONDED COMPLEX TRIMETHYLAMINE-HYDROGEN SULFIDE

Author Institution: Department of Chemistry, Kent State University; Department of Chemistry, Youngstown State UniversityRotational spectra have been recorded for six isotopomers of the trimethylamine-hydrogen sulfide complex using Fourier-transform microwave spectrometer. The spectra were found to be characteristic of a symmetric top, (B + C)/2= 1395.463 (1) MHz, and are indicative of free internal rotation of Trimethylamine within the complex A structure with a single, linear hydrogen bond ($R_{N-S} = 3.36 (5)$ Abest reproduces; the moments of inertia of the six isotopic species, including three distinct deuterated complexes. The experimental structure is compared to the ab initio structure optimized at the MP2/6-31G(d,p) level, which predicts $R_{N-S} = 3.328 \AA$. $MP2/aug^{\prime}-cc-pVTZ$ calculations were used to determine the binding energy of the complex and the barrier to an internal tunneling motion which exchanges the two $H_{2}S$ hydrogens