A helical structure with Z′=10

被引:35
作者
Hao, X [1 ]
Chen, J [1 ]
Cammers, A [1 ]
Parkin, S [1 ]
Brock, CP [1 ]
机构
[1] Univ Kentucky, Dept Chem, Lexington, KY 40506 USA
关键词
D O I
10.1107/S0108768105004076
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The structure of N ''-cyano-N, N-diisopropylguanidine, a push pull nitrile that includes the H2N - C=N - CN fragment, has been determined. Although the number of molecules in the asymmetric unit is exceptionally high (Z' = 10), there were no special crystallographic difficulties associated with data collection, structure solution or structure refinement because the individual molecules are small ( 12 non-H atoms) and because there is no important crystallographic pseudosymmetry. A complete set of N-H center dot center dot center dot N bonds is formed. Pairs of molecules form dimers, which associate to form ribbons that twist into a helix having five dimers per turn. The helices lie parallel to [ 101] and fit together with close contacts in three different directions perpendicular to that axis. The problems with optimizing so many different intermolecular contacts lead to a loosely packed structure.
引用
收藏
页码:218 / 226
页数:9
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