Infrared spectra of the OCS-CO2 complex: Observation of two distinct slipped near-parallel isomers

Abstract

Infrared spectra of OCS-CO(2) complexes are studied in a pulsed supersonic slit-jet expansion using a tunable diode laser probe in the 2060 cm(-1) region of the C-O stretching fundamental of OCS. Two bands are observed and analyzed, corresponding to two distinct isomers of the complex. Isomer a is the known form which has been previously studied in the microwave region. Isomer b is a new form, expected theoretically but first observed here. Structures are determined with the help of isotopic substitution. Both isomers are planar, with slipped near-parallel geometries. In isomer a, the intermolecular (center of mass) separation is 3.55 A and the C atom of the CO(2) is closer to the S atom of the OCS. In isomer b, the C atom of CO(2) slides closer to the O atom of OCS and the center of mass separation increases to 3.99 A. Isomer a is the lowest energy form, but paradoxically isomer b appears to be stronger in our infrared spectra. Predicted pure rotational transition frequencies are given to help in a search for the microwave spectrum of isomer b.

Xe⋯OCS: relatively straightforward?

“…The fact that we could observe the XeÁ Á ÁOCS complex is not particularly surprising, as many OCS complexes have been studied previously, including complexes of OCS with a single atom [3][4][5][6][7][8][9] or a di-/tri-atomic partner. [10][11][12] Initially, we thought that somebody must have studied this complex before, as it is the last one in series of OCS complexes with non-radioactive noble gases. However, it does not seem to be the case, and it is up to us to fill this particular gap in this series of homologues.…”

Theoretical studies of the N2O van der Waals dimer: Ab initio potential energy surface, intermolecular vibrations and rotational transition frequencies

“…1 It has been reported that one molecule of N 2 O has approximately 300 times the greenhouse warming potential of one molecule of CO 2 . The van der Waals (vdW) complexes of these "CO 2 family" molecules, especially their dimers [4][5][6][7][8][9][10][11][12][13][14][15][16][17] and trimers, [18][19][20] have been the focus of both experiment and theory over the past few years. 2,3 Therefore, the N 2 O molecule and N 2 O-including complexes are of particular interest in the field of atmospheric chemistry.…”

Xe···OCS: Relatively Straightforward?

“…The fact that we could observe the Xe• • •OCS complex is not particularly surprising, as many OCS complexes have been studied previously, including complexes of OCS with a single atom [3][4][5][6][7][8][9] or a di-/tri-atomic partner. [10][11][12] Initially, we thought that somebody must have studied this complex before, as it is the last one in series of OCS complexes with non-radioactive noble gases. However, it does not seem to be the case, and it is up to us to fill this particular gap in this series of homologues.…”