anti-Ethyl acetohydroximate

In the crystal structure of the title compound, C4H9NO2, the O—H⋯N hydrogen bonds link the molecules into supramolecular chains extending along the b-axis direction. The conformation of the NOH group in the nearly planar (r.m.s. deviation = 0.0546 Å) ethyl acetohydroximate molecule is trans to N=C.

In the crystal structure of the title compound, C 4 H 9 NO 2 , the O-HÁ Á ÁN hydrogen bonds link the molecules into supramolecular chains extending along the b-axis direction. The conformation of the NOH group in the nearly planar (r.m.s. deviation = 0.0546 Å ) ethyl acetohydroximate molecule is trans to N C.

Comment
Anti-ethyl acetohydroximate [systematic name: ethyl N-hydroxyacetimidate], (I), was investigated in a continuation of our studies of the IR spectra of hydrogen bonding in oxime derivatives (Flakus et al., 2012). In order to study interactions occurring via hydrogen bonds and molecular packing in this compound, we have now determined the structure of (I) using diffraction data collected at 100 K. Until now, the structures of syn-methyl acetohydroximate and syn-and antiethyl benzohydroximate were determined (Kjaer et al., 1977;Larsen et al., 1971). The crystal structure of syn-methyl acetohydroximate is composed of layers of molecules, which form cyclic, hydrogen-bonded trimers, whereas the crystals  (Allen et al., 1987). The conformation of the NOH group in the planar ethyl acetohydroximate molecule is trans to N=C. In the crystal, O-H···N are observed forming infinite chains along the b axis (Fig. 2) with a graph-set motif of C(3) (Etter et al., 1990;Bernstein et al., 1995).

Experimental
Ethyl acetohydroximate was purchased from Aldrich-Sigma. Crystals of title compound, suitable for X-ray diffraction, were selected directly from purchased sample.

Refinement
The H atoms were introduced in geometrically idealized positions with C-H distances of 0.99 Å and U iso (H) values set at 1.2U eq (C) for methylene group or 0.98 Å and with U iso (H) values set at 1.5U eq (C) for methyl groups. The H atom which takes part in hydrogen bonding was located in a difference Fourier map and was refined with U iso (H) value set at 1.5U eq (O).

Computing details
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2010).  The asymmetric unit of (I), with the atom-numbering scheme, showing 50% probability displacement ellipsoids. H atoms are shown as small spheres of arbitrary radius. 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.