Hydrogen-bonding in the pyrimidine⋯NH3 van der Waals complex: experiment and theory

2014 ◽  
Vol 16 (27) ◽  
pp. 14195-14205 ◽  
Author(s):  
M. P. Gosling ◽  
M. C. R. Cockett
Keyword(s):  
Hydrogen Bonding ◽  
Gas Phase ◽  
Van Der Waals ◽  
Van Der Waals Complex ◽  
Repulsive Interactions ◽  
Ring Nitrogen ◽  
Double Hydrogen ◽  
Hydrogen Bonded

The pyrimidine⋯NH3 complex exists as just a single double hydrogen-bonded structure in the gas phase with the ammonia favouring a position which shields it from repulsive interactions with the more remote ring-nitrogen.

Spectroscopic investigations of hydrogen bonding interactions in the gas phase. II. The determination of the geometry and potential constants of the hydrogen-bonded heterodimer CH 3 CN • • • HF from its microwave rotational spectrum

1980 ◽  
Vol 370 (1741) ◽  
pp. 239-255 ◽  
Keyword(s):  
Hydrogen Bonding ◽  
Gas Phase ◽  
Spectroscopic Constants ◽  
Rotational Spectrum ◽  
Hydrogen Bonding Interactions ◽  
Isotopic Species ◽  
Microwave Rotational Spectrum ◽  
Vibration Rotation ◽  
Hydrogen Bonded

The microwave rotational spectrum of the hydrogen-bonded heterodimer CH 3 CN • • • HF has been identified and shown to be characteristic of a symmetric top. A detailed analysis of several rotational transitions for a variety of isotopic species gives the spectroscopic constants summarized in the following table: Rotational constants/MHz, vibration-rotation constants/MHz and vibrational separations/cm -1 of CH 3 CN • • • HF

Erratum

1986 ◽  
Vol 404 (1826) ◽  
pp. 147-147 ◽  
Keyword(s):  
Hydrogen Bonding ◽  
Gas Phase ◽  
Ground State ◽  
Hyperfine Coupling ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Spectroscopic Investigations ◽  
Hydrogen Bonding Interactions ◽  
Hydrogen Bonded

Proc. R. Soc. Lond. A 401, 327-347 (1985) Spectroscopic investigations of hydrogen bonding interactions in the gas phase. X. Properties of the hydrogen-bonded heterodimer HCN⋯HF determined from hyperfine coupling and centrifugal distortion effects in its ground-state rotational spectrum By A. C. Legon, D. J. Millen and L. C. Willoughby On p. 327, at the end of the abstract, for 0.14 Å read 0.014 Å. On p. 343, line 7, for 0.025 Å read 0.014 Å. On p. 344, line 27, for 25.4° read 21.7°; line 33, for 6.6° read 2.9°. On p. 347, line 12, for 0.025 Å read 0.014 Å.

Stabilities in the gas phase of the hydrogen bonded complexes, YC6H4OH-X−, of substituted phenols, YC6E4OH, with the halide anions X− (Cl−, Br−, I−)

1990 ◽  
Vol 68 (11) ◽  
pp. 2070-2077 ◽  
Author(s):  
Gary J. C. Paul ◽  
Paul Kebarle
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Proton Transfer ◽  
Gas Phase ◽  
Equilibrium Constants ◽  
Substituent Effects ◽  
Closed Shell ◽  
Bond Energies ◽  
Substituted Phenols ◽  
Hydrogen Bonded

The equilibria, YPhOH + Br− = YPhOH-Br−, involving 26 differently substituted phenols, were determined with a pulsed high pressure mass spectrometer. The −ΔG0 evaluated from the equilibrium constants represent the hydrogen bond free energies in YPhOH-Br−. These data and data for X− = Cl− and I−, determined previously in this laboratory, are used to examine the substituent effects on the hydrogen bonding. It was found that the hydrogen bond energies in YPhOH-X− increase approximately linearly with the gas phase acidities of the phenols, YPhOH. This is in agreement with earlier observations that showed the bond energies in AH-B−, where AH were oxygen and nitrogen acids and B− closed shell anions, increase with increasing acidity of AH.A detailed analysis of the substituent effects, which is possible for YPhOH-X−, shows that the relationship with the acidity of AH can be divided into two parts. One is the increasing extent of actual proton transfer from AH on formation of the hydrogen bonded complex. Such proton transfer occurs in YPhOH-X− only for the series X− = Cl−. The second effect, which occurs for Cl− and is dominant for Br− and I−, is not directly related to the acidity of the phenols (or AH in general) but depends on a similarity of the substituent effects on the acidity and the stabilization of YPhOH-X− (or AH-B− in general). The dominant contribution to YPhOH-X− stabilization in this case is due to the field effects of the substituents, i.e., π delocalization plays only a small part. Therefore, the correlation with the acidity of YPhOH, where π delocalization is important, is not very close. Keywords: hydrogen bonding, substituent effects, ion–molecule equilibria, stability constants, thermochemistry.

Supersonic beam investigations of indole and indole–halomethane complexes: intermolecular interactions

1985 ◽  
Vol 63 (7) ◽  
pp. 1502-1509 ◽  
Author(s):  
James Hager ◽  
Stephen C. Wallace
Keyword(s):  
Hydrogen Bonding ◽  
Cell Membrane ◽  
General Anesthesia ◽  
Gas Phase ◽  
Intermolecular Interactions ◽  
Media Effects ◽  
Van Der Waals ◽  
Supersonic Jet ◽  
Electronic System ◽  
Induced Dipole

We report the findings of a supersonic beam investigation of the 1:1 gas phase complexes of indole with various halomethanes. The unique environment of the supersonic jet provides a method by which the pairwise intermolecular interactions of these complexes can be studied without the complications of condensed media effects. The behavior of argon and methane van der Waals molecules is described first in order to provide examples of simple dispersive interactions. These are then contrasted with complexing species such as CF4 and CCl4 where repulsive interactions offset the stabilization due to dispersive and dipole – induced dipole forces. Finally, we show that the interaction between the probe molecule and CHCl3 and CH2Cl2 is apparently hydrogen bonding with the indole π electronic system. The implications of these intermolecular interactions on the area of general anesthesia are discussed in terms of a picture in which both the hydrophobic and polar portions of cell membrane may be reversibly affected.

Ab initio Studies on Hydrazines: 2H-1,2,3-Triazol-2-amine With Special Reference to Its Equilibrium Structure and Vibrational Spectrum

1989 ◽  
Vol 42 (3) ◽  
pp. 433 ◽  
Author(s):  
NV Riggs
Keyword(s):  
Hydrogen Bonding ◽  
Vibrational Energy ◽  
Zero Point ◽  
Equilibrium Structure ◽  
Basis Sets ◽  
Transition Structure ◽  
Hydrogen Atoms ◽  
Ring Nitrogen ◽  
Experimental Values ◽  
Double Hydrogen

The geometries of four stationary structures of 2H-1,2,3-triazol-2-amine have been optimized with the 3-21G and 3-21G(N*) basis sets. The lowest-energy and only equilibrium structure predicted by these calculations is the 'perpendicular' Cs form (3), whereas infrared studies on benzo-annelated analogues had suggested it might be the 'parallel' Cs form (2) stabilized by 'double hydrogen-bonding' of the amino-hydrogen atoms to the flanking ring-nitrogen atoms. The latter form (2) is here characterized as the transition structure for rotation about the N-NH2 bond and, after zero-point vibrational-energy corrections, is calculated to lie 8.7 kJ mol-1 above the equilibrium structure (3) at HF/3-21G(N*) level or only 3.8 kJ mol-1 at MP4/6-31G** level. This very low barrier to internal rotation (cf. 26.5 kJ mol-1 for the analogous 1H-pyrrol-1-amine) may be due to double hydrogen-bonding of the kind suggested by the experimental study mentioned above. The transition structure for inversion at the NH2 centre is, as for 1H-pyrrol-1-amine, the perpendicular C2v structure (5), the barrier being 25.8 kJ mol-1 (cf. 24.5 kJ mol-1 for 1H-pyrrol-1-amine), and the planar C2v structure (4) is a second-order saddle point lying 41.7 kJ mol-1 above the equilibrium structure (3). Calculated NH-stretching frequencies, their separation, and relative intensities as compared with experimental values for benzo-annelated analogues offer broad support for the assignments above based on relative energies.

Sign in / Sign up

Export Citation Format

Share Document