Received 8 December 2010
The asymmetric unit of the title compound, C10H10N2O, contains two crystallographically independent molecules with similar geometries, which exist in the keto form. The C=O bond lengths are 1.2878 (12) Å in molecule A and 1.2890 (12) Å in molecule B, indicating that the compound undergoes enol-to-keto tautomerism during the crystallization process. In molecule A, the pyrazole ring is approximately planar [maximum deviation = 0.007 (1) Å] and forms a dihedral angle of 36.67 (6)° with the attached phenyl ring. In molecule B, the dihedral angle formed between the pyrazole ring [maximum deviation = 0.017 (1) Å] and the phenyl ring is 41.19 (6)°. In the crystal, intermolecular N-HO hydrogen bonds link neighbouring molecules into dimers generating R22(8) ring motifs. These dimers are linked into ribbons along  via intermolecular N-HO hydrogen bonds, forming R42(10) ring motifs.
For background to pyrazole derivatives and their antimicrobial activity, see: Ragavan et al. (2009, 2010). For bond-length data, see: Allen et al. (1987). For the structure of the enol form of this molecule, see: Shahani et al. (2010). For other related structures, see: Loh et al. (2010a,b,c). For hydrogen-bond motifs, 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: SJ5074 ).
HKF and WSL thank Universiti Sains Malaysia (USM) for the Research University Grant (1001/PFIZIK/811160). WSL also thanks the Malaysian government and USM for the award of a Research Fellowship. VV is grateful to the DST-India for funding through the Young Scientist Scheme (Fast Track Proposal).
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