N,N′-Bis(6-methyl-2-pyridyl)oxamide

In the crystal structure of the title compound, C14H14N4O2, the molecules are almost planar (mean deviation 0.028 Å) and a weak intramolecular N—H⋯O hydrogen bond between the H atom bound to an oxamide N atom and a carbonyl O atom is found. The asymmetric unit consits of one half-molecule which is located on a centre of inversion.

In the crystal structure of the title compound, C 14 H 14 N 4 O 2 , the molecules are almost planar (mean deviation 0.028 Å ) and a weak intramolecular N-HÁ Á ÁO hydrogen bond between the H atom bound to an oxamide N atom and a carbonyl O atom is found. The asymmetric unit consits of one half-molecule which is located on a centre of inversion.

N,N′-Bis(6-methyl-2-pyridyl)oxamide
Pei-Chi Cheng, Chia-Jun Wu and Jhy-Der Chen S1. Comment A series of Ag(I) coordination polymers containg N 1 ,N 2 -bis(2-pyridyl)oxamide ligands have been prepared, which show one-dimensional and two-dimensional structures (Hsu, et al., 2004;Hu, et al., 2004). To investigate the steric effect of the alkyl groups on the structural type of such coordination polymers, we have synthesized the title compound. Within this project its crystal structure was determined.
In its crystal structure weak intramolecular N-H···O hydrogen bonding is found (Tab. 1) and the molecules are almost planar ( Fig. 1).

S2. Experimental
2-Amino-6-methylpyridine (6.2 g, 57.3 mmol) was dissolved in 200 ml CH 2 Cl 2 , followed by addition of triethyl amine (10.0 ml, 72.1 mmol) at 0° C. The mixture was then stirred for 10 min. Oxalyl chloride (2.5 ml, 28.7 mmol) in 10 ml CH 2 Cl 2 was then added slowly to the above mixture. After continuous stirring for 3 h at 0° give maximu [C, 200 ml hexanes was added to the mixture to induce precipitate. The solid was filtered, washed with water to give a white product. Yield: 2.8 g (36%). Coloress plate crystals suitable for X-ray crystallography were obtained by slow evaporization of the solvent from a solution in CH 2 Cl 2 .

S3. Refinement
All the hydrogen atoms were placed into idealized positions and constrained by the riding atom approximation with C-H = 0.93 -0.96 Å, N-H = 0.86 Å and U iso (H) = 1.5 U eq (C) or 1.2 U eq (C, N). The methyl H atoms are disordered and were refined in two different orientations.  Crystal structure of the title compound with labeling and displacement ellipsoids drawn at the 30% probability level.

Special details
Experimental. 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. Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. 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 > 2sigma(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.  (11) 0.0441 (10) 0.0024 (9) −0.0038 (9) 0.0005 (8) Geometric parameters (Å, º)