Received 12 September 2011
In the title compound, C10H9ClN4O, the pyrazole ring [maximum deviation = 0.014 (2) Å] forms a dihedral angle of 7.06 (14)° with the chlorobenzene ring. The molecular conformation is stabilized by an intramolecular N-HO hydrogen bond, which generates an S(6) ring motif. In the crystal, inversion dimers linked by pairs of C-HO hydrogen bonds generate R22(16) ring motifs. The dimers are further connected by N-HN hydrogen bonds, thereby forming layers lying parallel to the bc plane.
For general background to and applications of pyrazole derivatives, see: Rai & Kalluraya (2006); Rai et al. (2008); Sridhar & Perumal (2003). For standard bond-length data, see: Allen et al. (1987). For graph-set notation, see: Bernstein et al. (1995). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB6405 ).
HKF and CKQ thank Universiti Sains Malaysia for the Research University Grant (No. 1001/PFIZIK/811160).
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