D. J. Pauley

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

Microwave spectra for the SO2⋅⋅⋅H2S, SO2⋅⋅⋅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, ΔJ=5.04(2) , ΔJK=65.46(9) , ΔK=−323(240) , δJ=0.63(1) and δK=38(3) kHz. For SO2⋅⋅⋅HDS, nine transitions yielded A=8229.7(6), B=1737.99(1), C=1519.69(2) MHz, ΔJ=4.4(4) and ΔJK=60(2) kHz, and for SO2⋅⋅⋅D2S, 11 transitions yielded A=8017.6(6), B=1715.24(2), C=1501.24(2) MHz, and ΔJ=3.8(4) , ΔJK=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 ...

The rotational spectra and centrifugal distortion parameters for the NNO–DF and ONN–DF complexes

Microwave measurements of rotational transitions for the linear ONN–DF and bent NNO–DF complexes were made using a pulsed‐beam, Fourier transform spectrometer. For ONN–DF, B=1808.959(2) MHz and DJ=2.79(6) kHz. Structure parameters are obtained and compared with ONN–HF parameters. For the bent NNO–DF isomer, seven new transitions and previous data were fit to obtain (A+ΔK)=25 988.4(3) MHz, B=2701.1(2) MHz, C=2422.3(2) MHz, ΔJ=0.052(3) MHz, ΔJK=−2.57(1) MHz, δJ=0.010(5) MHz, and δK=0.24(10) MHz. The centrifugal distortion constants for NNO–DF are used to obtain force field parameters  fRR and  fΘΘ describing motion of the DF center of mass relative to the NNO center of mass. The excellent agreement between these parameters and previous data on NNO–HF supports the simplified model used to describe the centrifugal distortion of this complex.

The rotational and tunneling spectrum of the H2S⋅CO2 van der Waals complex

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⋅CO2, allowed us to assign internal rotation, inversion tunneling states of the H2S and CO2 units in the complex. The following rotational constants were determined for the ground tunneling state of each species: for H2S⋅CO2, A=11 048.0(26) MHz, B=2147.786(4) MHz, and C=1806.468(4) MHz; for HDS⋅CO2, A=10 769(35) MHz, B=2107.26(24) MHz, and C=1775.83(24) MHz; and for D2S⋅CO2, A=10 356.2(28) MHz, B=2065.376(8) MHz, and C=1746.122(8) MHz. The electric dipole moments were determined for the H2S⋅CO2 and D2S⋅CO2 species, resulting in the values μa=0.410(14) D and μc=0.822(10) D for the H2S⋅CO2 species. The structure of the complex has ...

Microwave measurements and theoretical calculations on the structures of NNO–HCl complexes

Pulsed‐beam Fourier transform microwave spectroscopy was used to measure a and b dipole transitions for the N2O–H35Cl, N2O–H37Cl, N2O–D35Cl, and 15NNO–H35Cl van der Waals complexes. The observed transition frequencies were fit to determine the spectroscopic constants A–DK, B, C, DJ, DJK, eQqaa(Cl), and eQqbb(Cl). The structure of the complex appears to be a planar asymmetric top with a centers‐of‐mass separation Rc.m. ≊ 3.51 A. The angle θ between Rc.m. and the HCl axis is approximately 110°. The angle φ between the N2O axis and Rc.m. is approximately 77°. The structure was fit using a weighted least squares fit to B and C isotopic rotational constants with Rc.m., θ, and φ as the adjustable parameters, and this procedure yielded three local minima with standard deviations less than 5 MHz. Principal axis coordinates for the Cl, H, and terminal N atoms in the complex were determined with single isotopic Kraitchman analysis to aid in the selection of the ‘‘best’’ structure. In a second structural analysis Rc...

Microwave measurements on ArH2S, ArHDS and ArD2S complexes

Abstract Recent work on the H 2 OSO 2 complex revealed several previously unmeasured ArH 2 S transitions. In this work, microwave transitions for ArH s S, ArHDS and ArD 2 S complexes are reported and a structure analysis is presented. The observation of the new set of transitions assigned to a second ArHDS isomer indicates that the hydrogens of H 2 S are not rapidly exchanging H for D through internal rotation. The complex is unusual in that quite large differences in the vibrationally averaged structures are seen on isotopic substitution. The apparent presence in such weakly-bound complexes of several coupled modes with large amplitude vibrations causes difficulties in obtaining a single accurate equilibrium structure.

Microwave spectrum of the SO2-H2S complex

Abstract Ten Δ J = 1 rotational transitions for the SO 2 -H 2 S complex were observed in the 4–12 GHz frequency range using a pulsed-beam Fourier-transform microwave spectrometer. The complex is a near-prolate asymmetric top with 1 2 (B + C) = 1649(6) MHz and B - C = 228(10) MHz. Some of the observed transitions show inversion or hindered internal rotation splittings. A tentative structure is a non-planar cyclic complex containing two hydrogen bonds from H 2 S to the oxygen atoms on SO 2 .

Rotational transition and quadrupole coupling measurements on the NNO-HCN complex

Abstract Seven a -dipole and seven b -dipole transitions were measured for one isomer of the NNO-HCN complex using a pulsed-beam, Fourier transform microwave spectrometer. Rotational constants A +Δ K =10326.3(4) MHz, B =2814.32(14) MHz and C =2201.00(12) MHz and distortion constants Δ J =0.014(8) MHz and Δ JK =0.14(6) MHz were obtained by fitting the observed transition frequencies. A quadrupole coupling strength due to the HCN nitrogen of eQq aa =1.97±0.05 MHz was obtained by fitting low- J transitions. Approximate structural parameters are obtained using moments of inertia and quadrupole coupling data.