Microwave spectra and structure for SO₂⋯H₂S, SO₂⋯HDS, and SO₂⋯D₂S complexes

Microwave spectra for the SO₂⋯H₂S, SO ₂⋯HDS, and SO₂⋯D₂S complexes were measured using a pulsed beam, Fourier transform microwave spectrometer. Both a-dipole and c-dipole transitions were obtained. A total of 24 transitions were obtained for SO₂⋯H₂S, yielding A = 8447.3(2), B = 1762.004(7), C= 1538.483(7) MHz, Δ_J = 5.04(2), Δ_JK = 65.46(9), Δ_K = -323(240), δ_J = 0.63(1) and δ_K = 38(3) kHz. For SO ₂⋯HDS, nine transitions yielded A = 8229.7(6), B = 1737.99(1), C= 1519.69(2) MHz, Δ_J = 4.4(4) and Δ_JK = 60(2) kHz, and for SO₂⋯D₂S, 11 transitions yielded A = 8017.6(6), B = 1715.24(2), C = 1501.24(2) MHz, and Δ_J = 3.8(4), Δ_JK = 51(2) kHz. For the H₂S data only, there are four possible structures for the complex which fit the data. When the deuterium isotope data are included, only two possible structures fit the data. There is only one structure which allows two O⋯H hydrogen bonds, and this is the structure we favor. This analysis basically gives a "stacked" structure with two O⋯H hydrogen bonds and a near van der Waals radius contact between the two sulfur atoms.