Water in weak interactions: The structure of the water–nitrous oxide complex

Abstract

Articles you may be interested inNon-covalent interactions of nitrous oxide with aromatic compounds: Spectroscopic and computational evidence for the formation of 1:1 complexesThe rotational spectra of 0, and HDO-N 2 0 have been observed using molecular beam electric resonance techniques at both zero and nonzero electric fields. H z O-N 2 0 is nonrigid with respect to internal rotation of the water subunit. Rotational constants in MHz for the spatially antisymmetric tunneling state are A = 12605.001 (77), B=4437.978(32), and C=3264.302(32). Rotational constants for the spatially symmetric tunneling state are A= 12622.595(203), B=4437.422 (47), C=3264.962(47). These together with the rotational constants of the other isotopomers are consistent with a planar, Tshaped arrangement of the heavy atoms of the complex, with the distance between the centers of mass of the two subunits, R c . m ., equal to 2.91 (2) A or a distance of 2.97(2) A from the H 2 0 oxygen to the central nitrogen of N 2 0. The measured dipole moments of the two tunneling isomers are identical; JLa = 1.480(2) and JLb = 0.31 (2) D. The values of these dipole moment components indicate an in-plane equilibrium tilt of about 20° between the C 2v axis of water and the N-O weak bond. This tilt suggests a second interaction may exist between a hydrogen on water and the N 2 0 subunit. The rotational constants suggest that the N 2 0 unit is tilted by about 9° from perpendicular to the N-O weak bond. The barrier for the tunneling interchange of the water protons is estimated to be 235 ( 10) em -I. Quadrupole coupling constants eqQaa for the outer and inner nitrogen of N 2 0 are 0.371 (130) and 0.128(45) MHz, respectively. Electrostatic models applied to water-N 2 0 and water-CO z predict hydrogen bonded structures rather than the experimentally observed Lewis base structures.

High-Resolution IR Spectroscopy of the N2O–H2O and N2O–D2O van der Waals Complexes

“…This is in agreement with the assumption that the N 2 O axis lies almost perpendicular to the a-axis of the complex. The lack of c-type transitions confirms the planarity of the complex, as was already, found in the microwave experiments (13). For N 2 O-H 2 O a doubling of the lines was found, with one line being decreased in intensity by a factor of 2-4 compared to the blue-shifted component.…”

“…The infrared transitions were fit simultaneously with the microwave data of reference (13). As expected, the results for the ground state is in excellent agreement with the result of the fit of the rotational constants in the previous microwave study with the only exception that the distortion constants could be improved due to the increased number of transitions involving higher J levels.…”

“…The only previous measurements on N 2 O-H 2 O were carried out by Zolandz et al in the microwave region (13). They recorded rotational spectra of N 2 O-H 2 O, N 2 O-D 2 O, and N 2 O-HDO and derived rotational and centrifugal distortion constants.…”

Overtone spectroscopy of molecular complexes containing small polyatomic molecules

“…A typical analysis was carried out for HDO-N 2 O, with spectra recorded at T rot = 20 K. MW data [252] were simultaneously fitted. The S/N was unfortunately too limited to reliably extract lifetimes from observed linewidths in all of the overtone-excited complexes so far mentioned in this subsection.…”

“…The main focus of the analysis came from ab initio calculations to elucidate the geometrical structure of HDO-N 2 O. It was known to be planar, with the oxygen end of NNO closer to one of the water bonds [252,253]. As it turns out, however the literature analyses did not consider the existence of two conformers with either the OH or the OD bond almost parallel to the linear N 2 O monomer.…”