An investigation of the hydrogen‐bonded dimer H3N⋅⋅⋅HBr by pulsed‐nozzle, Fourier‐transform microwave spectroscopy of ammonium bromide vapor

1987 ◽  
Vol 86 (12) ◽  
pp. 6722-6730 ◽  
Author(s):  
N. W. Howard ◽  
A. C. Legon
Keyword(s):  
Fourier Transform ◽  
Microwave Spectroscopy ◽  
Ammonium Bromide ◽  
Fourier Transform Microwave Spectroscopy ◽  
Pulsed Nozzle ◽  
Hydrogen Bonded

Rotational spectrum and properties of the hydrogen-bonded heterodimer H 2 O· · · HCN from pulsed-nozzle, Fourier-transform microwave spectroscopy

1984 ◽  
Vol 396 (1811) ◽  
pp. 405-423 ◽  
Keyword(s):  
Fourier Transform ◽  
Microwave Spectroscopy ◽  
Coupling Constants ◽  
Spectroscopic Constants ◽  
Rotational Spectrum ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Fourier Transform Microwave Spectroscopy ◽  
Pulsed Nozzle ◽  
Hydrogen Bonded

The ground state rotational spectrum of a hydrogen-bonded heterodimer formed from water and hydrogen cyanide has been detected and measured by using the technique of pulsed-nozzle, Fourier-transform microwave spectroscopy. Rotational constants ( B 0 , C 0 ) centrifugal distortion constants ( ∆ J , ∆ JK ) and, where appropriate, 14 N-, D- or 17 O-nuclear quadrupole coupling constants have been determined for the following isotopic species; H 2 16 O· · · HC 14 N, H 2 18 O· · · HC 14 N, H 2 16 O· · · HC 15 N, HD 16 O· · · HC 15 N, D 2 16 O· · · HC 15 N, H 2 16 O· · · DC 15 N, HD 16 O· · · DC 15 N and H 2 17 O· · · HC 15 N. An analysis of these spectroscopic constants indicates that the heterodimer is effectively planar, with a pair of equivalent protons and the arrangement H 2 O· · · HCN. The intermolecular interaction is through a hydrogen bond between HCN and H 2 O and the distance between the O and C nuclei r (O· · · C) is 3.157 Å (1Å = 10 -10 m). An interpretation of the nuclear quadrupole coupling constants leads to the conclusion that arccos <cos 2 Φ > ½ ≈ 51°, where Φ is the angle between the local C 2 axis of H 2 O and the a -axis of the complex; and that arccos <cos 2 θ > ½ ≈ 10°, where θ is the angle between the HCN axis and the a -axis. The intermolecular stretching force constant k σ = 11 Nm -1 has been determined from ∆ J .

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