The structure of N2⋅SO2 from diode laser and molecular‐beam electric resonance spectroscopy

Tetrel, pnictogen and chalcogen bonds identified in the gas phase before they had names: a systematic look at non-covalent interactions

Tetrel, pnictogen and chalcogen-bonded complexes: old bonds but new names.

Microwave Rotational Spectral Study of SO2-CO

The microwave spectrum of the molecular complex of sulfur dioxide (SO₂) with carbon monoxide (CO) has been studied with a pulsed-beam Fourier Transform Microwave Spectrometer (FTMW) from a pair of gas samples of 1 % by volume of SO₂ and CO in Ar, and introduced via separate capillary inputs to the flow nozzle. The frequency coverage was about 7 GHz to 16 GHz for various isotopomers. The molecular structure was determined with the aid of spectral studies of isotopically substituted monomers containing ¹³C, ¹⁸O and ³⁴S. The rotational analyses provide the rotational and centrifugal distortion constants for all of the isotopomers analyzed. The structure determination is compared to detailed ab initio structural calculations. The electric dipole moment components along the a- and c-axis were determined from Stark effect measurements.

The Dynamics of N(2)-O(3) and N(2)-SO(2) Probed by Microwave Spectroscopy

The microwave spectra of N(2)-O(3) and N(2)-SO(2) have been recorded in the 6-18 GHz range using a pulsed-nozzle, Fourier transform microwave spectrometer. C-type transitions have been observed for both complexes which are slightly shifted by internal tunneling motions of the O(3) or SO(2) moieties. In addition, unshifted a-type transitions have been observed for N(2)-O(3). The nuclear hyperfine pattern is typical of equivalent nitrogen nuclei. Two sets of rotational and hyperfine constants are required to fit the symmetric and antisymmetric nuclear spin states, indicating that the equivalence arises from tunneling rotation of the nitrogen molecule. Internal tunneling motions along three tunneling pathways have been identified, although no information on the N(2) tunneling frequency is available from the spectra. From the N(2)-O(3) data the tunneling frequencies cannot be decorrelated from the rotational parameters; however, the O(3) tunneling frequency upper limit is estimated to be 2.0 MHz and the frequency of the concerted tunneling motion of both moieties is estimated to be about 8.9 MHz. For N(2)-SO(2), the SO(2) tunneling frequency is 11.5 kHz and the concerted frequency 173.9 kHz. Both complexes are roughly T shaped with the N(2) axis approximately perpendicular to the O(3) or SO(2) plane. In the equilibrium structures of both complexes, the a-c inertial plane is a plane of symmetry. The centers of mass separations are estimated from the rotational parameters to be 3.582 Å for N(2)-O(3) and 3.875 Å for N(2)-SO(2). The angle between the symmetry axes of the O(3) or SO(2) and the line joining their centers of mass have been calculated as 130.84 degrees (or 49.16 degrees ) and 119.71 degrees (or 60.29 degrees ), respectively. From the quadrupole analysis, the average angle between the N(2) axis and the a-inertial axis is 32.12 degrees for N(2)-O(3) and 27.81 degrees for N(2)-SO(2). Model electrostatic and ab initio calculations confirm these structures. Differences between the experimental and calculated structural parameters highlight the role of tunneling dynamics in these complexes. Copyright 2000 Academic Press.

Dipole Moment Function of LiF and LiCl Obtained from the Herman-Wallis Analysis: A Comparative Study with the MBER Data

FTIR absorption spectra of the fundamental bands of LiF and LiCl were measured with an apodized resolution of 0.01 cm-1. The Herman-Wallis analysis of these spectra led to the determination of the ratio of the dipole derivative to the permanent dipole moment, [µe/(dµ/dr)ere], for each molecule. The vibrational dependence of the dipole moment for each molecule has been already reported and these data were reanalyzed to determine the dipole moment function independently. The results from the Herman-Wallis analysis were compared with these results, and good agreement was found. This demonstrates that the Herman-Wallis analysis can produce reliable relative values of dipole moment functions. Copyright 1999 Academic Press.