N,N-Diethyl-5-nitropyridin-2-amine

In continuation of our studies of organic molecules with nonlinear optical properties (Yufit et al., 2006), an attempt to grow crystals of 2-adamantylamino-5-nitropyridine (AANP) (Tomaru et al., 1991; Antipin et al., 2001) by sublimation has been made. As a result, two types of crystals formed in the reaction vessel. An X-ray study of the small cubic-shaped ones revealed that they are, in fact, crystals of N,N-diethyl-5nitropyridine-2-amine, (I), which is a side product in the synthesis of AANP. Here, we briefly describe the structural features of this compound.

In the title compound, C 9 H 13 N 3 O 2 , the asymmetric unit contains two almost identical but crystallographically independent molecules. The molecules are linked together by pairs of weak C-HÁ Á ÁO interactions into zigzag chains, which, in turn, form corrugated layers perpendicular to the a axis.

Comment
In continuation of our studies of organic molecules with nonlinear optical properties (Yufit et al., 2006), an attempt to grow crystals of 2-adamantylamino-5-nitropyridine (AANP) (Tomaru et al., 1991;Antipin et al., 2001) by sublimation has been made. As a result, two types of crystals formed in the reaction vessel. An X-ray study of the small cubic-shaped ones revealed that they are, in fact, crystals of N,N-diethyl-5nitropyridine-2-amine, (I), which is a side product in the synthesis of AANP. Here, we briefly describe the structural features of this compound.
The asymmetric unit of (I) contains two virtually identical but crystallographically independent molecules (Fig. 1). These molecules differ slightly in the positions of the terminal C atoms of the ethyl groups (Fig. 2).
The packing of the molecules of (I) is quite different from that of its benzene analogue N,N-diethyl-p-nitroaniline (Maurin & Krygowski, 1988), in which numerous C-HÁ Á Á interactions are present.

Figure 1
The asymmetric unit of the title compound, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

Experimental
The title compound, (I), was isolated by chromatography from the mixture of products of the reaction between 2-chloronitropyridine (0.948 g, 5.979 mmol) and adamantylamine (0.984 g, 6.594 mmol). The crystals of (I) were formed on heating the powder sample at 343 K for 3 d (yield 0.99 g, 61%; m.p. 440 K).  )/3 (Á/) max = 0.001 Á max = 0.29 e Å À3 Á min = À0.19 e Å À3 Table 1 Selected geometric parameters (Å , ).  The chains of molecules of (I) in a single layer. H atoms of ethyl groups have been omitted for clarity. Dashed lines indicate hydrogen bonds.

Figure 2
A least-squares fit of the pyridine rings of the two independent molecules.  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.