Acta Cryst. (2010). E66, o887-o888  [ doi:10.1107/S1600536810009438 ]

Ethyl (2E)-2-(hydroxyimino)propanoate

I. V. Nikolayenko, C. Bazzicalupi, G. P. Thubron and C. Grimmer

Abstract: The molecule of the title compound, C₅H₉NO₃, is essentially planar [the maximum deviation for a non-H atom from the mean plane is 0.021 (3) Å] due to the -conjugation of the hydroxyimino and carbonyl groups, which are trans to each other; ab initio calculations in vacuo at the DFT (B3LYP/6-311G**++) level of theory confirmed that E conformer is indeed the lowest in energy. The packing in crystal structure is influenced by strong intermolecular O-HN hydrogen-bonding interactions between oxime groups and also by -stacking of the molecules due to the carbonyl and oxime group orbital overlap [interplanar distance between adjacent molecules = 3.143 (4) Å]. Jointly, these factors afford infinite 6.32 Å thick molecular sheets, where the plane of each molecule is perpendicular to the plane of the sheet. Seen from above, the molecules within the sheet are arranged in a herringbone pattern. Such sheets form a stack due to weak van der Waals interactions; the gap between adjacent sheets is 2.07 Å.

Online 20 March 2010

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