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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 40, Number 3
JKCSEZ 40(3)
June 20, 1996 

 
Title
The Crystal and Molecular Structure of 6-Ethyl-5,6-Dihydrouracil

6-에틸-5,6-디히드로우라실의 결정 및 분자구조
Author
Choong Tai Ahn

안중태
Keywords
Abstract
6-ethyl-5,6-dihydrouracil(C6H10N2O2)은 단사정계인 공간군 P21/c으로 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)=304이며, F > 4.0 σ(F)인 1070개의 관측된 회절점에 대한 R값은 0.054 였다. 직접법에 의하여 구조를 풀었으며, 전행열-최소자승법에 의하여 정밀화하였고, C-H 결합길이는 0.96Å에 고정하였다. Hydrouracil 고리는 불규칙한 puckered 각을 가진 envelope conformation으로 되어 있고, 고리에 붙어 있는 에틸기는 axial 방향으로 향하고 있으며, 단위 격자속에는 100평면에 거의 평행인 2차원의 결합망을 이룬, 두개의 분자간 수소결합, N(1)-H---O(7)(1+x, 0.5-y, -0.5+z)와 N(3)-H---O(7)(1+x, 0.5-y, 0.5+z)가 있으며, 이웃 분자와의 최단 거리는 C(4)---O(8)(-x, -y, 1-z)의 3.187Å이다.

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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161 - 166
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