Experimental charge density and electrostatic potential in nicotinamide

Abstract

The accurate crystal structure of nicotinamide, 3-pyridinecarboxamide, was determined from X-ray and neutron diffraction experiments: C(6)H(6)N(2)O, M(r) = 122.13, monoclinic, P2(1)/c, Z = 4. The electron distribution at 150 K was determined by the maximum entropy method and the electrostatic potential in the crystal was calculated by Fourier convolution of the electron distribution. The electrostatic properties of the nicotinamide molecule depend on the molecular conformation. The asymmetric electrostatic potential field observed above and below the pyridine-ring plane is related to the rotation of the carboxamide group with respect to the pyridine plane. The positive potential peak at the C4 atom of the pyridine ring extends to the C=O-group side of the plane. The asymmetry of the potential on the C4 atom is consistent with the stereospecificity of hydride transfer in NAD(+)/NADH oxidoreduction.

Synthesis, Crystal Structure, Magnetic, Thermal and Fluorescent Properties of [Co(H2O)4(nia)2](suc)·(H2suc)

“…The coordination sphere around the cobalt(II) ion is distorted octahedral. The geometrical parameters of the nicotinamide ligands are normal [23]. The planar pyridine ring and the amide group plane are mutually twisted by 5.4(1)…”

Dimer formation in nicotinamide and picolinamide in the gas and condensed phases probed by infrared spectroscopy

“…3.5 Å ). 23 Two intermolecular hydrogen bonds are established by the amide group, one with the oxygen atom of a neighbouring molecule and the second one with the pyridine nitrogen atom of a third molecule (at 295 K the H 2 NÁ Á ÁO 0 and H 2 NÁ Á ÁN (pyr) 00 distances were found to be 2.991 and 3.105 Å , respectively) 23 (Scheme 3). In contrast, PA crystallizes in two modifications (both belonging to the monoclinic space group P2 1 /a, with 4 molecules in the unit cell).…”

“…The fact that the preferred crystalline arrangements in NA 22,23 and PA 24 (whose molecular structures are closely related) involve different basic units, with the centrosymmetric dimer existing in the two known crystalline modifications of PA 24 and being absent in the crystal of NA, 22,23 caught our attention and stimulated us to investigate the structures and relative energies of the relevant dimeric structures in these two molecules. The case of NA appeared particularly interesting, since it might be an exception to the general tendency of amides to form centrosymmetric dimers.…”

“…According to previous structural studies [22][23][24] the basic units in the crystals of NA and PA are different. The NA crystal was found to be monoclinic, P2 1 /c (a = 3.98, b = 15.63, c = 9.44 Å , b = 99.01, at 295 K), with 4 molecules per unit cell.…”

6-Aminonicotinamide

“…The torsion angle O1-C6-C1-C2 of -23.55 (18) is indicative of a syn conformation of the carbonyl to the pyridine N atom. This conformation is opposite to that of any of the polymorphs of the parent unsubstituted compound, nicotinamide, where the torsion angle ranges from -157.6 (1) to 167.1 (1)° (Miwa et al, 1999;Li et al, 2011). The hydrogen bonding of (I) makes use of all four hydrogen atom donors, two on the amide group and two on the amine.…”