Rotational spectrum of the weakly bonded C6H6-H2S dimer and comparisons to C6H6-H2O dimer

Arunan, E. ; Emilsson, T. ; Gutowsky, H. S. ; Fraser, Gerald T. ; de Oliveira, G. ; Dykstra, C. E. (2002) Rotational spectrum of the weakly bonded C6H6-H2S dimer and comparisons to C6H6-H2O dimer Journal of Chemical Physics, 117 (21). p. 9766. ISSN 0021-9606

Full text not available from this repository.

Official URL:

Related URL:


Two symmetric-top, ΔJ = 1 progressions were observed for the C6H6-H2S dimer using a pulsed nozzle Fourier transform microwave spectrometer. The ground-state rotational constants for C6H6-H2S are B=1168.53759(5)MHz, DJ= 1.4424(7)kHz and DJK=13.634(2)kHz. The other state observed has a smaller B of 1140.580(1) MHz but requires a negative DJ=−13.80(5)kHz and higher order (H) terms to fit the data. Rotational spectra for the isotopomers C6H6-H234S, C6H6-H233S, C6H6-HDS, C6H6-D2S and 13CC5H6-H2S were also obtained. Except for the dimer with HDS, all other isotopomers gave two progressions like the most abundant isotopomer. Analysis of the ground-state data indicates that H2S is located on the C6 axis of the C6H6 with a c.m. (C6H6)-S distance of 3.818 Å. The angle between the a axis of the dimer and the C2v axis of the H2S is determined to be 28.5°. The C6 axis of C6H6 is nearly coincident with a axis of the dimer. Stark measurements of the two states led to dipole moments of 1.14(2) D for the ground state and 0.96(6) D for the other state. A third progression was observed for C6H6–H2S which appear to have K ≠ 0 lines split by several MHz, suggesting a nonzero projection of the internal rotation angular momentum of H2S on the dimer a axis. The observation of three different states suggests that the H2S is rotating in a nearly spherical potential leading to three internal rotor states, two of which have Mj = 0 and one having Mj = ±1,Mj being the projection of internal rotational angular momentum on to the a axis of the dimer. The nuclear quadrupole hyperfine constant of the 33S nucleus in the dimer is determined for the two symmetric-top progressions and they are -17.11MHz for the ground state and -8.45MHz for the other state, consistent with the assignment to two different internal-rotor states. The 17O quadrupole coupling constant for the two states of C6H6-H2O were measured for comparison and it turned out to be nearly the same in the ground and excited internal rotor state, −1.89 and −1.99MHz, respectively. The rotational spectrum of the C6H6-H2S complex is very different from that of the C6H6-H2O complex. Model potential calculations predict small barriers of 227, 121, and 356cm−1 for rotation about a, b and c axes of H2S, respectively, giving quantitative support for the experimental conclusion that H2S is effectively freely rotating in a nearly spherical potential. For the C6H6-H2O complex, the corresponding barriers are 365, 298 and 590cm−1.

Item Type:Article
Source:Copyright of this article belongs to American Institute of Physics.
Keywords:Organic Compounds; Hydrogen Compounds; Rotational States; Fourier Transform Spectra; Microwave Spectra; Ground States; Rotational Isomerism
ID Code:48221
Deposited On:14 Jul 2011 06:48
Last Modified:14 Jul 2011 06:48

Repository Staff Only: item control page