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KMID : 1059519960400030161
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Journal of the Korean Chemical Society
1996 Volume.40 No. 3 p.161 ~ p.166
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The Crystal and Molecular Structure of 6-Ethyl-5,6-Dihydrouracil
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Ahn Choong-Tai
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Abstract
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6-ethyl-5,6-dihydrouracil(C6H10N2O2) is monoclinic, space group P21/c with a=10.302(2), b=10.419(3), c=7.095(1)Å, β=106.6(0), Z=4, V=729.7(3)Å3, Dc=1.29 g/cm3, λ(Mo Kα)=0.71073Å, μ=0.010 cm-1, F(000)=304, and R=0.054 for 1070 unique observed reflection with F > 4.0 σ(F). The structure was solved by direct methods and refined by full-matrix least-squares refinement with the fixed C-H bond length at 0.96Å. The hydrouracil molecule makes an envelope conformation with the ethyl substituent oriented to an axial position attainable to a varying degree of steric strain. There are two intermolecular hydrogen-bondings via N-H---O interactions, being nearly parallel to the 100 plane. The shortest distance between molecules is 3.187Å of C(4) and O(8) (-x, -y, 1-z).
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