Inter- and intramolecular hydrogen bonds – Structures of 1-methylpyrrole-2-carboxamide and 1-hydroxypyrrole-2-carboxamide (original) (raw)
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Journal of Molecular Structure, 2006
The two crystal structures of 5-chloro-2-hydroxy-benzamide and 2-hydroxy-N,N-diethyl-benzamide were determined by X-ray diffraction at 100 K. The intramolecular and intermolecular hydrogen bonds were found in these structurally similar 2-hydroxy-benzamides. Analysis of the hydrogen bonding was carried out on the basis of X-ray data, infrared spectra, and DFT calculations. Disruption of the intramolecular hydrogen bonding in the solid state by a steric effect is shown. Conformational analysis and potential energy calculations as functions of the turning angle around the C aryl-C alkyl bond were conducted. The values obtained for the HOMA index indicate mutual compensation of the amide and hydroxyl groups (due to the high degree aromaticity of the phenyl ring).
NMR and conformational studies of new 5‐phenylpyrrole‐carboxamide derivatives
Magnetic Resonance in Chemistry, 2009
The 1H and 13C NMR resonances of 22 5‐(5‐substituted‐2‐nitrophenyl)‐1H‐pyrrole‐2‐carboxamides, 22 5‐(5‐substituted‐2‐aminophenyl)‐1H‐pyrrole‐2‐carboxamides, and 9 5‐phenyl‐1H‐pyrrole‐2‐carboxamides were assigned completely using the concerted application of one‐ and two‐dimensional experiments (DEPT, gs‐HMQC and gs‐HMBC). NOE studies and conformational analysis confirm the preferred conformations of such compounds. Copyright © 2009 John Wiley & Sons, Ltd.
Unconventional hydrogen bonding and π-stacking in two substituted pyridine carboxamides
Acta crystallographica. Section C, Crystal structure communications, 2010
The crystal structures of two para-substituted aryl derivatives of pyridine-2-carboxamide, namely N-(4-fluorophenyl)pyridine-2-carboxamide, C(12)H(9)FN(2)O, (I), and N-(4-nitrophenyl)pyridine-2-carboxamide, C(12)H(9)N(3)O(3), (II), have been studied. Compound (I) exhibits unconventional aryl-carbonyl C-H...O and pyridine-fluorine C-H...F hydrogen bonding in two dimensions and well defined π-stacking involving pyridine rings in the third dimension. The conformation of (II) is more nearly planar than that of (I) and the intermolecular interactions comprise one-dimensional aryl-carbonyl C-H...O hydrogen bonds leading to a stepped or staircase-like progression of loosely π-stacked molecules. The close-packed layers of planar π-stacked molecules are related by inversion symmetry. Two alternating interplanar separations of 3.439 (1) and 3.476 (1) Å are observed in the crystal lattice and are consistent with a repetitive packing sequence, ABA'B'AB…, for the π-stacked inversion pair...
Journal of the American Chemical Society, 1985
is observed for the average C-C bond lengths, which increase drastically from the three-to the four-membered ring and decrease steadily for the larger rings. The flap angle a of the CNC plane increases with ring size, i.e., with decreasing angle strain. The direction of the amino hydrogen atom alternates with ring size. In the four-membered ring, the N-H bond is in equatorial direction and the axial conformer does not e~i s t .~~-~' In the five-membered ring, the preferred conformer is axial, and in the (48) Robiette, A. G.; Borgers, T. R.; Strauss, H. L. Mol. Phys. 1981, 42, (49) Cremer, D.; Dorofeeva, 0. V.; Mastryukov, V. S. J. Mol. Struci. (50) Skancke, P. N.; Fogarasi, G.; Boggs, J. E. J. Mol. Sirucf. 1980, 62, (51) Note Added in Proof A recent gas-phase NMR study of azetidine (Friedman, B. R.; Chauvel, J. P.; True, N. S. J . Am. Chem. SOC. 1984,106, 7638-7639) is interpreted in terms of a 1.00/0.32 ratio of equatorial/axial conformers. In the microwave very weak transitions, which on the basis of their quadrupole hyperfine structure can be assigned to the axial conformer, indicate a considerably higher energy difference between axial and equatorial conformers. 151 9-1 524. 1981, 75, 225-240. 259-273.
Structure and Conformation of Solvated 1-(4-methoxybenzenesulfonyl)-5-oxo-pyrrolidine-2-carboxamide
Crystal Research and Technology, 2002
The crystal structure and molecular conformation of solvated 1-(4-methoxybenzenesulfonyl)-5-oxopyrrolidine-2-carboxamide (C 12 H 14 O 5 N 2 S.H 2 O), synthesized and biologically evaluated as a possible antineoplastic agent, have been studied by X-ray analysis and AM1 molecular orbital methods. The compound crystallizes in the monoclinic space group P2 1 , with a = 9.661(4), b = 7.246(3), c = 11.378(5)Å, β = 113.42(2)°, Z= 2. The structure has been solved by direct methods and refined to R = 0.0438 for 1721 observed reflections. The crystal structure consists of an essentially planar methoxyphenyl ring linked to a 2-carboxamide substituted oxo-pyrrolidine moiety via sulfonyl group and a lattice water molecule. The conformational analysis of the title compound investigated by semiempirical quantum mechanical AM1 calculations shows a good agreement with the X-ray structure except a rotation of the carboxamide moiety about the C (oxo-pyrrolidine)-C (carboxamide) bond. In the solid state, the molecules translated in the b-direction are linked by intermolecular N-H⋅⋅⋅O hydrogen bonds to form infinite one-dimensional chain.
Journal of Chemical Crystallography, 2012
The title compound, 2-pyridinecarboxamide, C 6 H 6 N 2 O, crystallize in the monoclinic system with space group P2 1 /n (N˚14), Z = 4, and unit cell parameters a = 5.2074(1) Å, b = 7.1004(1) Å, c = 16.2531(3) Å, = 100.260(1)˚. The crystal structure of the title compound, was reported previously from Weissenberg photographic data with R = 0.127. It has now been redetermined, providing a significant increase in the precision of the derived geometric parameters. The crystal packing is governed by N-H•••O hydrogen bond-type intermolecular interactions, forming infinite one-dimensional chains with graph-set notation C(4), R 2 2 (8) and R 2 4 (8).
Canadian Journal of Chemistry, 1992
ZAIHUI ZHANG, STEVEN J. RETTIG, and CHRIS ORVIG. Can. J. Chem. 70, 763 (1992). 3-Hydroxy-I-carboxymethyl-2-methyl-4-pyridinone (Hcmp) and 3-hydroxy-I-(p-rnethoxypheny1)-2-methyl-4-pyridine (Hpap) have been prepared and studie! by single crystal X-ray diffraction. Crystals of Hcmp are monoclinic, a = 6.340 (2), b = 7.705 (I), c = 16.226 (1) A, P = 94.74 (I), Z = 4, space group P 2 , / n and those for Hpap are monoclinic, a = 10.8435 (9), b = 16.680 (2), c = 13.5665 (6) A, P = 109.450 (4), Z = 8, space group C 2 / c . Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to R = 0.030 and 0.041 (R,, = 0.039 and 0.058) for 1642 and 1819 reflections with I 2 3u(I), respectively. Bond lengths and bond angles in the two compounds are normal; however, Hcmp forms as a zwitterion in the solld state. The two compounds were also studied by mass spectrometry, UV, infrared, proton NMR spectroscopies, and potentiometric equllibnum measurements. The protonation constants for Hcrnp are log Kl = 9.76 (I), log K2 = 3.43 (I), and log K, = 2.78 (3) and for Hpap are log K ; = 9.42 (4) and log K ; = 3.16 (8). .
The Journal of Physical Chemistry A, 2005
The structure and vibrational spectra of hexamethylpyrromethene (HMPM) have been investigated by X-ray crystallography, IR and Raman spectroscopies, and density functional theory calculations. HMPM crystallizes in the form of dimers, which are held together by bifurcated N-H(‚‚‚N) 2 hydrogen bonds, involving one intramolecular and one intermolecular N-H‚‚‚N interaction. The monomers are essentially planar, and the mean planes of the monomers lie approximately perpendicular to one another, so that the four N atoms in the dimer form a distorted tetrahedron. The structure of the HMPM dimer is well-reproduced by B3LYP/6-31G* calculations. A comparison of the calculated geometry of the dimer with that of the monomer reveals only small changes in the N-H‚‚‚N entity and the methine bridge angles upon dimerization. These are a result of weakening of the intramolecular N-H‚‚‚N hydrogen bond and the formation of a more linear N-H‚‚‚N intermolecular hydrogen bond. Using an empirical relation between the shift of the N-H stretching frequency of pyrrole and the enthalpy of adduct formation with bases [Nozari, M. S.; Drago, R. S. J. Am. Chem. Soc. 1970, 92, 7086-7090], estimates of the strength of the intra-and intermolecular hydrogen bonds are obtained. IR and Raman spectroscopies of HMPM and its isotopomers deuterated at the pyrrolic nitrogen atom and at the methine bridge reveal that the molecule is monomeric in nonpolar organic solvents but dimeric in a solid Ar matrix and in KBr pellets. The matrix IR spectra show a splitting of vibrational modes for the dimer, particularly those involving the N-H coordinates. Due to intrinsic deficiencies of the B3LYP/6-31G* approximation, a satisfactory reproduction of these modes of the monomeric and dimeric HMPM requires specific adjustments of the NH scaling factors for the calculated force constants and, in the case of the NH out-of-plane modes of HMPM dimers, also of intra-and intermolecular coupling constants. This parametrization does not significantly affect the other calculated modes, which in general reveal a very good agreement with the experimental data.