Knowledge Bank

The rotational spectra of $H2S$$CO2$ and two deuterated forms have been observed using a pulsed beam Fourier transform microwave spectrometer. For each of the three complexes we assign a-type and c-type transitions which are split into a weak'' and a strong'' intensity component. The analysis based on that previously used for the $(H2O)2$ complex and modified for application to $H2S\cdot CO2$ allowed us to assign two internal rotations within the complex. The following rotational constants were determined: $$\begin{array}{llll}&A (MHz)& B (MHz)& C (MHz)\ H_{2}S\cdot CO_{2} &10783.54 (18)& 2147.63 (17) &1806.61 (17)\ HDS\cdot CO_{2} & 10782.94 (4200)& 2107.26 (23)& 1775.88 (23)\ D_{2}S\cdot CO_{2} & 10359.39 (600) &2065.37 (1) &1746.09 (1)\\end{array}$$ Two structures are possible for the complex. Both have the $CO2$ and the S atom of $H2S$ in a T-shaped configuration. The $H2S$ plane is situated out of the $CO2$-S plane with the hydrogens pointing either toward ($\Theta =64\circ$) or away ($\Theta =116\circ$) from the $CO2$. This is determined by assuming the total dipole moment. $\mu T$, for $H2S\cdot CO2$ the complex ($T=0.918(24)D$) is due to the $H2S$ dipole ($\mu b=H2S)=0.9783$). For either the $\Theta =64\circ$ or $\Theta =116\circ$ structure the $Rcm$ bond distance for $H2S\cdot CO2$ is 3.494(24){\AA}. The importance of the structure of this complex to applications in the area of bimolecular reaction dynamics will be discussed.