X-ray and DFT studies of the structure, vibrational and NMR spectra of 2-amino-pyridine betaine hydrochloride
The effect of hydrogen bonding, inter- and intramolecular electrostatic interactions on the conformation of 2-amino-pyridine betaine hydrochloride (1-carboxymethyl-2-amino-pyridinium chloride), 2-NH 2PBH⋯Cl(c), in the crystal and its isolated molecules has been studied by X-ray diffraction, FT-IR, R...
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Published in | Journal of molecular structure Vol. 744; pp. 59 - 73 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier B.V
03.06.2005
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Online Access | Get full text |
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Summary: | The effect of hydrogen bonding, inter- and intramolecular electrostatic interactions on the conformation of 2-amino-pyridine betaine hydrochloride (1-carboxymethyl-2-amino-pyridinium chloride), 2-NH
2PBH⋯Cl(c), in the crystal and its isolated molecules has been studied by X-ray diffraction, FT-IR, Raman,
1H and
13C NMR spectroscopies, and by DFT calculations. In the crystal, the Cl
− anion is connected with protonated betaine via hydrogen bond, O–H⋯Cl
−= 2.975(2)
Å, two N(12)–H⋯Cl
− hydrogen bonds and two N(1) H⋯Cl
− intermolecular electrostatic interactions. Two minima are located in the potential energy surface at the B3LYP/6-31G(d,p) level, 2-NH
2PBH⋯Cl(t) and 2-NH
2PB⋯HCl(c), with the latter being 20,7
kcal/mol higher in energy. The optimized bond lengths and angles of 2-NH
2PBH⋯Cl(t) at B3LYP level of theory are in good agreement with X-ray data, except for the conformation of the COOH group, which is
cis (
syn) in the crystal and
trans (
anti) in the single molecule. The probable assignments for the anharmonic experimental solid state vibrational spectra of 2-NH
2PBH⋯Cl(c) and 2-ND
2PBD⋯Cl(c) based on the calculated B3LYP/6-31G(d,p) harmonic frequencies have been made.
1H and
13C NMR screening constants for both single molecules have been calculated in the GIAO/B3LYP/6-31G(d,p) approach. Linear correlation between the calculated and experimental
1H chemical shifts holds only for
cis conformer. The lack of such a correlation for
trans conformer indicates that it is absent in D
2O solution. |
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ISSN: | 0022-2860 1872-8014 |
DOI: | 10.1016/j.molstruc.2004.11.087 |