15min:

MAUSUMI GOSWAMI AND E. ARUNAN, Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India.

Rotational Spectra of phenylacetylene-H₂S, phenylacetylene-HDS, phenylacetylene-D₂S, phenylacetylene-H₂³⁴S, C₈H₅D-H₂S have been measured. The spectra were recorded using a Balle-Flygare type PNFT Microwave spectrometer[1]. Helium was used as a carrier gas for these measurements. Both `a' and `b' dipole transitions have been observed. For the parent isotopomer, all the transitions are split into two. The rotational spectra of phenylacetylene-HDS indicate that the splitting is due to the interchange of equivalent hydrogens of H₂S unit in the complex. The measured rotational constants of the parent species are A = 1206.551(7) MHz, B = 1134.152(6) MHz, C = 732.192(6) MHz for the stronger series and A = 1206.732(7)MHz, B = 1134.056(6) MHz, C = 732.141(8) MHz for the weaker series. The constants derived from the experiments confirm a structure where H₂S is placed perpendicular to the plane of the phenylacetylene molecule. This study reveals that the binding of H₂O and H₂S to the phenylacetylene molecule is very different. Microwave spectroscopic investigations confirmed that H₂O prefers to be in plane of the phenylacetylene, donating one of its hydrogen to the acetylenic cloud while the oxygen of H₂O is involved in a secondary interaction forming C-H---O hydrogen bond with the ring hydrogen ortho to the acetylenic group[2].

\bigskip 1. Arunan et al. Current Science ,82(2002)533.

skip 2. TA04, 63rd International Symposium on Molecular Spectroscopy ,Columbus, June 16-20, 2008.