(2E)-2-(2-Phenylhydrazin-1-ylidene)propanoic acid

The 13 non-H atoms comprising the title compound, C9H10N2O2, are close to planar (r.m.s. deviation = 0.140 Å), with maximum deviations of 0.292 (1) and 0.210 (1) Å to either side of the least-squares plane exhibited by the hydroxy and carbonyl O atoms, respectively. The observed conformation is stabilized by an intramolecular O—H⋯N hydrogen bond. The conformation about the N=C double bond [1.2909 (16) Å] is E. The hydroxy OH group also forms an intermolecular hydrogen bond to a carbonyl O atom, and the amine H atom similarly forms an N—H⋯O hydrogen bond to a second carbonyl O atom. The result is the formation of a double layer with a flat topology. Layers stack along the a-axis direction connected by C—H⋯π interactions.

The 13 non-H atoms comprising the title compound, C 9 H 10 N 2 O 2 , are close to planar (r.m.s. deviation = 0.140 Å ), with maximum deviations of 0.292 (1) and 0.210 (1) Å to either side of the least-squares plane exhibited by the hydroxy and carbonyl O atoms, respectively. The observed conformation is stabilized by an intramolecular O-HÁ Á ÁN hydrogen bond. The conformation about the N C double bond [1.2909 (16) Å ] is E. The hydroxy OH group also forms an intermolecular hydrogen bond to a carbonyl O atom, and the amine H atom similarly forms an N-HÁ Á ÁO hydrogen bond to a second carbonyl O atom. The result is the formation of a double layer with a flat topology. Layers stack along the a-axis direction connected by C-HÁ Á Á interactions.

Related literature
For background and recent studies on the biological activity of tin/organotin compounds, see: Gielen & Tiekink (2005) Table 1 Hydrogen-bond geometry (Å , ).
This work was financially supported by the Ministry of Science Technology and Innovation (MOSTI) under a research grant (No. 06-01-09-SF0046). The authors would like to thank Universiti Malaysia Sarawak (UNIMAS) for the facilities to carry out the research work. The authors also thank the University of Malaya for support of the crystallographic facility.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HG5024).

Comment
The title compound, (I), was prepared as a potential ligand for tin (Affan et al., 2009), motivated by the wide range of biological activities displayed by organotin compounds (Gielen & Tiekink, 2005). The r.m.s. for the 13 non-hydrogen atoms comprising (I), Fig. 1, is 0.140 Å. The maximum deviations are found for the carboxylic acid-O atoms with the O1 atom being 0.292 (1) Å out of the least-squares plane and the O2 lying 0.210 (1) Å to the other side. The planarity in the molecule is readily explained in terms of an intramolecular O-H···N hydrogen bond as the hydroxy H is directed toward the centre of the molecule,

Refinement
Carbon-bound H-atoms were placed in calculated positions (C-H = 0.95 to 0.98 Å) and were included in the refinement in the riding model approximation, with U iso (H) set to 1.2-1.5U eq (C). The O-H and N-H hydrogen atoms were freely refined; see Table 1 for bond distances. Fig. 1. The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids at the 50% probability level.

Figures
supplementary materials sup-2  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 Rfactors(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.