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organic compounds
The monosubstituted derivative 4-ethynyl[2.2]paracyclophane, C18H16, (I), and the four disubstituted isomers, 4,12-, (II), 4,13-, (III), 4,15-, (IV), and 4,16-diethynyl[2.2]paracyclophane, (V), all C20H16, show the usual distortions of the [2.2]paracyclophane framework. The crystal packing is analyzed in terms of C—H
π interactions, some with Hπ as short as 2.47 Å, in which the cyclophane rings and/or the triple-bond systems may act as acceptors. For compounds (I) and (IV), the known `7,11'-type cyclophane packing is observed, with a herring-bone pattern of molecules in a layer structure.
π interactions, some with Hπ as short as 2.47 Å, in which the cyclophane rings and/or the triple-bond systems may act as acceptors. For compounds (I) and (IV), the known `7,11'-type cyclophane packing is observed, with a herring-bone pattern of molecules in a layer structure.organic compounds
In the title compound, C18H16, the [2.2]paracyclophane geometry is restrained to a considerable extent despite the introduction of the extra C=C bridge; typical paracyclophane features, such as the elongated C-C bridges, are still observed. However, the bridgehead atoms of the C=C bridge are forced into unusually close proximity [2.657 (3) Å], which in turn causes the rings to be rotated to an interplanar angle of 13.7 (2)°. The packing involves hexagonally close-packed layers of molecules parallel to the xy plane, corresponding to the known `7,11' pattern of paracyclophanes, but without significant short intermolecular contacts.
organic compounds
![[triple bond]](/logos/entities/z-tbnd_rmgif.gif)
C hydrogen bonds in the structures of two poly(cyano)-substituted ring systemsIn benzene-1,2,3-tricarbonitrile, C9H3N3, the packing of the two independent molecules is three-dimensional and complex, involving inter alia bifurcated (C—H)2N systems from neighbouring CH groups. In [2.2]paracyclophane-4,5,12,13-tetracarbonitrile, C20H12N4, the [2.2]paracyclophane systems display the usual distortions, namely lengthened C—C bonds and widened sp3 angles in the bridges, narrow angles in the six-membered rings at the bridgehead atoms, and flattened boat conformations of the rings. The molecules are linked by a series of C—HN interactions to form layers parallel to the ab plane.
N systems from neighbouring CH groups. In [2.2]paracyclophane-4,5,12,13-tetracarbonitrile, C20H12N4, the [2.2]paracyclophane systems display the usual distortions, namely lengthened C—C bonds and widened sp3 angles in the bridges, narrow angles in the six-membered rings at the bridgehead atoms, and flattened boat conformations of the rings. The molecules are linked by a series of C—HN interactions to form layers parallel to the ab plane.
