Polarizability, proton transfer and symmetry of energy surfaces of carboxylic acid—N-base hydrogen bonds. Infrared investigations

1977 ◽  
Vol 73 (6) ◽  
pp. 788-803 ◽  
Author(s):  
Rainald Lindemann ◽  
Georg Zundel
Keyword(s):  
Carboxylic Acid ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Energy Surfaces

scholarly journals Crystal structure of (E)-2-[(4-hydroxybenzylidene)azaniumyl]benzoate

2014 ◽  
Vol 70 (9) ◽  
pp. o1008-o1008 ◽  
Author(s):  
M. Nawaz Tahir ◽  
Abdul Haleem Khan ◽  
Hazoor Ahmad Shad
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Schiff Base ◽  
Carboxylic Acid ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Dihedral Angle ◽  
Acid Group ◽  
Aromatic Rings ◽  
Carboxylic Acid Group

The title Schiff base, C14H11NO3, crystallizes as a zwitterion (i.e.proton transfer from the carboxylic acid group to the imine N atom). The dihedral angle between the aromatic rings is 19.59 (6)° and an intramolecular N—H...O hydrogen bond closes anS(6) ring. In the crystal, inversion dimers linked by pairs of O—H...O hydrogen bonds generateR24(24) loops. The dimers are linked by C—H...O interactions, generating (211) sheets.

Comparison of the proton-transfer path in hydrogen bonds from theoretical potential-energy surfaces and the concept of conservation of bond order. II. (N—H...N)+ hydrogen bonds

2007 ◽  
Vol 63 (4) ◽  
pp. 650-662 ◽  
Author(s):  
Irena Majerz ◽  
Ivar Olovsson
Keyword(s):  
Hydrogen Bonds ◽  
Potential Energy ◽  
Proton Transfer ◽  
Potential Energy Surfaces ◽  
Bond Order ◽  
Theoretical Calculations ◽  
Perfect Agreement ◽  
Reaction Coordinates ◽  
Donor And Acceptor ◽  
Energy Surfaces

The quantum-mechanically derived reaction coordinates (QMRC) for the proton transfer in (N—H—N)+ hydrogen bonds have been derived from ab initio calculations of potential-energy surfaces. A comparison is made between the QMRC and the corresponding bond-order reaction coordinates (BORC) derived by applying the Pauling bond-order concept together with the principle of conservation of bond order. We find virtually perfect agreement between the QMRC and the BORC for intermolecular (N—H—N)+ hydrogen bonds. In contrast, for intramolecular (N—H—N)+ hydrogen bonds, the donor and acceptor parts of the molecule impose strong constraints on the N—N distance and the QMRC does not follow the BORC relation in the whole range. The X-ray determined hydrogen positions are not located exactly at the theoretically calculated potential-energy minima, but instead at the point where the QMRC and the BORC coincide with each other. On the other hand, the optimized hydrogen positions, with other atoms in the cation fixed as in the crystal structure, are closer to these energy minima. Inclusion of the closest neighbours in the theoretical calculations has a rather small effect on the optimized hydrogen positions. [Part I: Olovsson (2006). Z. Phys. Chem. 220, 797–810.]

scholarly journals 2-Carboxylatopyridinium–4-nitrophenol (1/1)

2014 ◽  
Vol 70 (4) ◽  
pp. o450-o450 ◽  
Author(s):  
A. Sankar ◽  
S. Ambalatharasu ◽  
G. Peramaiyan ◽  
G. Chakkaravarthi ◽  
R. Kanagadurai
Keyword(s):  
Carboxylic Acid ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Three Dimensional ◽  
Acid Group ◽  
Pyridine Molecule ◽  
Carboxylic Acid Group ◽  
Title 1 ◽  
Dimensional Network

In the title 1:1 adduct, C6H5NO3·C6H5NO2, both molecules are almost planar (r.m.s. deviations for the non-H atoms = 0.027 and 0.023 Å for 4-nitrophenol and 2-carboxylatopyridinium, respectively). The pyridine molecule crystallizes as a zwitterion (nominal proton transfer from the carboxylic acid group to the N atom in the ring). In the crystal, inversion dimers of the zwitterions linked by pairs of N—H...O hydrogen bonds generateR22(10) loops; two 4-nitrophenol molecules link to the dimer by O—H...O hydrogen bonds, generating a four-molecule aggregate. These are linked by C—H...O interactions, forming a three-dimensional network.

Carboxylic Acid-N Base Hydrogen Bonds with Large Proton Polarizability in Acetonitrile as a Function of the Basicity of the Hydrogen Bond Acceptors

1984 ◽  
Vol 39 (10) ◽  
pp. 986-992 ◽  
Author(s):  
Gunnar Albrecht ◽  
Georg Zundel
Keyword(s):  
Hydrogen Bond ◽  
Carboxylic Acid ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Linear Relation ◽  
Equilibrium Constants ◽  
Association Constants ◽  
The Right ◽  
Intrinsic Effect ◽  
Association Equilibrium

Abstract Carboxylic acid-N base systems are studied in acetonitrile. The association equilibrium constants Ka and the proton transfer equilibrium constants KPT in the OH···N ⇄ O-···H+N bonds formed, are determined from IR spectra. The association constants Ka increase in proportion to the basicity of the hydrogen bond acceptors. The same is true with regard to the proton transfer constants. The OH ···N ⇄ O- ···H+N equilibria are shifted with increasing basicity to the right hand side. It is discussed that this shift is caused by an intrinsic effect as well as by an extrinsic one (interaction of the dipole of the hydrogen bond with its environment). A linear relation exists between log KPT and ⊿pKa (pKa of the protonated base minus pKa of the acid). 50% transfer of the protons to the N base is found at ⊿pKa = 2.6. As indicated by intense continua. these hydrogen bonds show large proton polarizability if the degree of asymmetry of their proton potentials is not too large.

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