3-Carbamoyl-1-(2-nitrobenzyl)pyridinium bromide

In the title compound, C13H12N3O3 +·Br−, the benzene and pyridinium rings form a dihedral angle of 82.0 (1)°. In the crystal, N—H⋯Br and N—H⋯O hydrogen bonds link the components into chains along [001]. In addition, weak C—H⋯O and C—H⋯Br hydrogen bonds are observed.


Experimental
Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL. One of the most important challenges in applying mono-oxygenases reactions in vitro is to find an effective regeneration system for the necessary co-enzyme (mostly NAD(P)H) (Hollmann et al., 2001;Lee et al.,2011;Maenaka et al., 2012;Park et al., 2008;Ruppert et al., 1988;Zhu et al., 2006). The well established methods for the regeneration of the nicotinamide co-enzyme mainly consist of an enzyme-coupled approach utilizing formate dehydrogenase or glucose-6phosphate dehydrogenase. Because the redox coenzyme couple NADH/NAD + is ubiquitous and controls so much of our oxidation/reduction nature, there has been a long-standing interest in the mechanisms of the redox interconversions (Zhu et al., 2003). The high cost of these co-factors, however, is prohibitive of industrialization of many promising enzymatic processes. An efficient method of their in situ regeneration is the only means for making the processes economically and industrially feasible (Song et al., 2008). Therefore, many researchers have given considerable attention to the chemistry of NADH and its models (Hollmann et al., 2001). In this work, we have synthesized the title compound as a NAD + model and report herein its crystal structure.
The molecular structure of the title compound is shown in Fig. 1. The benzene ring (C8-C13) and pyridine ring (N3/C2-C6) form a dihedral angle of 82.0 (1)°. In the crystal, intermolecular N-H···Br and N-H···O hydrogen bonds link the components to form chains along [001]. In addition, weak C-H···O and C-H···Br hydrogen bonds are observed.

Experimental
Nicotinamide (123.4 mg, 1 mmol) was dissolved in 10 ml acetonitrile. After stirring for a few minutes, 2-nitrobenzyl bromide (220.4 mg, 1 mmol) was carefully added to the reaction mixture. The solution was stirred for 3 h at 353K. The precipitate was filtered, washed three times with methylene chloride, and dried under vacuum. Crystals suitable for X-ray analysis were obtained from a methanol soution of the title compound in a few days.

Refinement
H atoms bonded to C atoms were placed in calculated positions with C-H distances of 0.93 Å for aromatic C atoms and 0.97 Å for a methylene C atoms. They were included in the refinement in riding-motion approximation with U iso (H) = 1.2U eq (C). The positions of N-H atoms of the amine were refined with N-H = 0.860 (2) Å and U iso (H) =1.2U eq (N).

Computing details
Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).  The molecular structure with displacement ellipsoids shown at the 50% probability level. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq