Journal of the Korean Chemical Society (대한화학회지)

Korean Chemical Society (대한화학회)
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The Crystal and Molecular Structure of 6-Ethyl-5,6-Dihydrouracil

6-에틸-5,6-디히드로우라실의 결정 및 분자구조

  • An, Choong Tai (Department of Chemistry, Hankuk University of Foreign Studies)
  • 안중태 (한국외국어대학교 자연과학대학 화학과)
  • Published : 19960300
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Abstract

6-ethyl-5,6-dihydrouracil($C_6H_10N_2O_2$) is monoclinic, space group $$P2_{1}c}$$ with a=10.302(2), b=10.419(3), $c=7.095(1)\AA$, $\beta=106.6(0)$, Z=4, $V=729.7(3)\AA$^3$$, $D_c=1.29 g/cm^3,\;{\lambda}(MoK\alpha)=0.71073\AA$, $\mu=0.010cm^{-1}$, F(000)=304, and R=0.054 for 1070 unique observed reflection with F>4.0 $\sigma(F).$ The structure was solved by direct methods and refined by full-matrix least-squares refinement with the fixed C-H bond length at $0.96\AA.$ 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 $3.187\AA$ of C(4) and O(8) (-x,-y, 1-z).

6-ethyl-5,-6-dihydrouracil($C_6H_10N_2O_2$)은 단사정계인 공간군 $P2_{1c}$으로 a=10.302(2), b=10.419(3), $c=7.095(1)\AA$, $\beta=106.6(0)^{\circ}$, Z=4, $V=729.7(3)\AA^3$, $D_c=1.29g/cm^3,\;{\lambda}(MoK\alpha)=0.71073\AA$, $\mu=0.010$cm^{-1}$, F(000)=304이며, F>4.0 $\sigma(F)$인 1070개의 관측된 회절점에 대한 R값은 0.054였다. 직접법에 의하여 구조를 풀었으며, 전행열-최소자승법에 의하여 정밀화하였고, C-H 결합길이는 $0.96\AA$에 고정하였다. Hydrouracil 고리는 불규칙한 puckered 각을 가진 envelope conformation으로 되어 있고, 고리에 붙어 있는 에틸기는 axial 방향으로 향하고 있으며, 단위격자속에는 100평면에 거의 평행인 2차원의 결합망을 이룬, 두 개의 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 최단거리는 C(4)---O(8)(-x, -y, 1-z)의 $3.187\AA$이다.

Keywords

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