Infrared spectrum of the CS2 trimer: observation of a structure with D3 symmetry

Abstract

Infrared spectra of a carbon disulfide trimer formed in a pulsed supersonic slit-jet expansion are obtained via direct absorption of a tuneable diode laser in the region of the CS(2)ν(3) fundamental (∼1535 cm(-1)). This is the first high-resolution spectroscopic observation of (CS(2))(3). Two bands sharing the same lower state are assigned to ((12)C(32)S(2))(3). These correspond to the two infrared active trimer vibrations (a parallel and a perpendicular band) of the constituent CS(2) monomer asymmetric stretches. The weaker perpendicular band is centered at 1524.613 cm(-1), shifted by -10.74 cm(-1) with respect to the free CS(2) monomer. The parallel band is centered at 1545.669 cm(-1), a vibrational shift of +10.31 cm(-1). Transitions with K≠ 3n and those with K = 0, J = odd in the ground state are absent, establishing that this trimer has D(3) symmetry. The two parameters required to define this structure are determined to be 3.811 Å for the C-C bond distance and 61.8° for the angle between a monomer axis and the plane containing the C atoms. In addition, a parallel band arising from trimers with a single (34)S substitution is observed around 1544.46 cm(-1). Together with the recently observed cross-shaped CS(2) dimer, these results indicate a tendency for CS(2) to form highly symmetric clusters.

Infrared spectra of rare gas–carbon disulfide complexes: He–CS2, Ne–CS2, and Ar–CS2

“…But even here it turns out that there is a difference, since a higher-energy cross-shaped isomer of OCS-CS 2 has now been detected [11] which has no counterpart for OCS-CO 2 . Finally, there are the cross-shaped CS 2 dimer [12] and the D 3 symmetry CS 2 trimer [13] recently observed by our group. In both cases, the structure differs from the CO 2 analogs.…”

“…Our experimental results using a He + CS 2 mixture covered a wider range in the CS 2 m 3 region than those with Ne or Ar because these same spectra were also used to study (CS 2 ) 2 and (CS 2 ) 3 [12,13]. As it turns out, the 1534.13 cm À1 band [12] of (CS 2 ) 2 interferes somewhat with the P-branch of He-CS 2 , but leaves the R-branch (shown in the lower panel of Fig.…”

Assessing the non-ideality of the CO2-CS2 system at molecular level: A Raman scattering study

“…92 Incidentally, we note that even in the gaseous phase of pure CS 2 , molecules tend to form highly symmetric clusters as the presence of dimers, trimers, and tetramers has been recently put in evidence by infrared spectroscopy in supersonic jet expansion of gas mixture of CS 2 in helium. [14][15][16] Harsh-repulsive forces which govern the short range local ordering in liquids and contribute to the packing of CS 2 molecules via the molecular shape must play a relevant role in favouring the formation of clusters. 94 The free molecular volume 95 in pure CS 2 calculated from the molecular and van der Waals volumes 96 is about 28 Å 3 , whereas it is about 38 Å 3 for CO 2 .…”

“…In gaseous phase, investigations have been mainly devoted to the analysis of the Fermi resonance coupling of vibrational modes of the isolated molecule, [1][2][3] and to the characterisation of the structure of weakly bounded clusters. [4][5][6][7][8][9][10][11][12][13][14][15][16][17] In dense phase, the aim was to provide insight on the nature and time scale of the intermolecular interactions from "allowed" vibrational spectra or from the analysis of collision induced (CI) spectra which are unique probes of the multi-body interactions. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] The study of the interaction of carbon dioxide with molecular liquids and complex fluids as ionic liquids is a field of current interest, motivated not only from the fundamental point of view but mainly under the impetuous motivation of understanding the interactions of CO 2 in the field of environmental studies.…”

Efficient and accurate treatment of weak pairs in local CCSD(T) calculations

“…As a result, LCCSD(T)|LMP2 overestimates E int of the experimental geometry by 2.5 kcal/mol, while the error reduces to less than TABLE V. Intermolecular interaction energies E int , correlation contributions of the local triples correction, E T (all in kcal/mol) of (CS 2 ) 3 for two different interatomic or intermolecular distances R (in Å) and two different tilting angles α. R = 3.811Å, α = 28.2 • is the experimental geometry reported in Ref. 64, R = 3.65 Å corresponds to the LMP2 minimum, and α = 0 • to a parallel arrangement of the three CS 2 molecules. In parentheses the differences of the individual E int relative to the experimental geometry are given.…”