4-Chloro-1H-pyrrolo[2,3-d]pyrimidine

The title compound, C6H4ClN3, is essentially planar with the pyrrole and pyrimidine rings inclined to one another by 0.79 (15)°. In the crystal, molecules are connected via pairs of N—H⋯N hydrogen bonds, forming inversion dimers. These dimers are linked via C—H⋯N interactions, forming a two-dimensional network parallel to (10-1).


Su-Lan Dong and Xiaochun Cheng Comment
The title compound is an important organic intermediate that has been used to synthesis a drug which has shown promising activity against HCV replication (Chang et al., 2010).
The molecular structure of the title molecule is shown in Fig. 1. The bond lengths (Allen et al., 1987) and angles are within normal ranges. The molecule is planar with the pyrrole ring (N1/C2-C5) and pyrimidine ring (N2/N3/C1/C2/C5/C6) being inclined to one another by only 0.79 (15)°.
In the crystal, molecules are connected via a pair of N-H···N hydrogen bonds to form inversion dimers, which are further linked via C-H···N interactions (Table 1 and Fig. 2). This results in the formation of a two-dimensional network parallel to (1 0 -1).

Experimental
The title compound was prepared by a method reported in the literature (Chang et al., 2010). A solution of phosphoryl trichloride (22.7 g, 158 mmol) in dichloromethane (50 ml) was added slowly to a solution of 3H-pyrrolo[2,3d]pyrimidin-4(4aH)-one (10 g, 74 mmol). After being stirred for 6 h at reflux temperature, the solvent was filtered and the organic phase was evaporated on a rotary evaporator and gave the title compound. Colourless block-like crystals, suitable for X-ray diffraction analysis, were obtained by dissolving the solid (0.5 g, 3.26 mmol) in ethanol (25 ml) and evaporating the solvent slowly at room temperature for about 7d.

Refinement
All the H atoms were positioned geometrically and constrained to ride on their parent: N-H = 0.86 Å, C-H = 0.93 Å with U iso (H) = 1.2U eq (N,C).

Figure 2
A view along the a axis of the crystal packing of the title compound. The N-H···N and C-H···N hydrogen bonds are shown as dashed lines (see Table 1 for details]. 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.