Acta Crystallographica Section C

Crystal Structure Communications

Volume 69, Part 3 (March 2013)

organic compounds

Acta Cryst. (2013). C69, 258-262    [ doi:10.1107/S0108270113002369 ]

An X-ray crystallographic and density functional theory study of (3Z)-4-(5-ethyl­sulfonyl-2-hy­droxy­anilino)pent-3-en-2-one and (3Z)-4-(5-tert-butyl-2-hy­droxy­anilino)pent-3-en-2-one

K. J. Akerman and O. Q. Munro

Abstract: The Schiff base enaminones (3Z)-4-(5-ethyl­sulfonyl-2-hy­droxy­anilino)pent-3-en-2-one, C13H17NO4S, (I), and (3Z)-4-(5-tert-butyl-2-hy­droxy­anilino)pent-3-en-2-one, C15H21NO2, (II), were studied by X-ray crystallography and density functional theory (DFT). Although the keto tautomer of these compounds is dominant, the O=C-C=C-N bond lengths are consistent with some electron delocalization and partial enol character. Both (I) and (II) are nonplanar, with the amino-phenol group canted relative to the rest of the mol­ecule; the twist about the N(enamine)-C(aryl) bond leads to dihedral angles of 40.5 (2) and -116.7 (1)° for (I) and (II), respectively. Compound (I) has a bifurcated intra­molecular hydrogen bond between the N-H group and the flanking carbonyl and hydroxy O atoms, as well as an inter­molecular hydrogen bond, leading to an infinite one-dimensional hydrogen-bonded chain. Compound (II) has one intra­molecular hydrogen bond and one inter­molecular C=O...H-O hydrogen bond, and consequently also forms a one-dimensional hydrogen-bonded chain. The DFT-calculated structures [in vacuo, B3LYP/6-311G(d,p) level] for the keto tautomers compare favourably with the X-ray crystal structures of (I) and (II), confirming the dominance of the keto tautomer. The simulations indicate that the keto tautomers are 20.55 and 18.86 kJ mol-1 lower in energy than the enol tautomers for (I) and (II), respectively.

Formula: C13H17NO4S and C15H21NO2

hkldisplay filedownload file

Structure factor file (CIF format) (130.0 kbytes)
[ doi:10.1107/S0108270113002369/yp3023Isup2.hkl ]
Contains datablock I

hkldisplay filedownload file

Structure factor file (CIF format) (130.3 kbytes)
[ doi:10.1107/S0108270113002369/yp3023IIsup3.hkl ]
Contains datablock II


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