Acta Crystallographica Section C

Crystal Structure Communications

Volume 62, Part 5 (May 2006)

organic compounds

av3005 scheme

Acta Cryst. (2006). C62, o289-o294 [ doi:10.1107/S0108270106011243 ]

Unusual conformations of 1,3-dialkoxythiacalix[4]arenes in the solid state

O. Kasyan, I. Thondorf, M. Bolte, V. Kalchenko and V. Böhmer

Abstract: The structures of three syn-1,3-dialkoxythiacalix[4]arenes with unusual conformations in the solid state are reported. The pinched cone conformation of syn-2²,4²-dihydroxy-1²,3²-bis(prop-2-enyloxy)thiacalix[4]arene, C₃₀H₂₄O₄S₄, (3a), is stabilized by two intramolecular hydrogen bonds, remarkably formed from both OH groups to the same ether O atom. In syn-2²,4²-dihydroxy-1⁵,2⁵,3⁵,4⁵-tetranitro-1²,3²-bis(prop-2-enyloxy)thiacalix[4]arene acetone disolvate, C₃₀H₂₀N₄O₁₂S₄·2C₃H₆O, (3b1), the molecule is found in the 1,3-alternate conformation. The crystallographic C2 symmetry is due to a twofold rotation axis running through the centre of the calixarene ring. The hydroxy groups cannot form intramolecular hydrogen bonds as in (3a) and both are bonded to an acetone solvent molecule. The molecule of the pseudo-polymorph of (3b1) in which the same compound crystallized without any solvent, viz. (3b2), is located on a crystallographic mirror plane. Only one of the two hydroxy groups forms a hydrogen bond, and this is with a nitro group of a neighbouring molecule as acceptor. Molecular mechanics calculations for syn-1,3-diethers suggest a preference of the 1,3-alternate over the usual cone conformation for thiacalix[4]arene versus calix[4]arene and for para-nitro versus para-H derivatives.

Formula: C₃₀H₂₄O₄S₄, C₃₀H₂₀N₄O₁₂S₄·2C₃H₆O and C₃₀H₂₀N₄O₁₂S₄


	Structure factor file (CIF format) (297.3 kbytes) [ doi:10.1107/S0108270106011243/av30053asup2.hkl ] Contains datablock boeh43

	Structure factor file (CIF format) (226.3 kbytes) [ doi:10.1107/S0108270106011243/av30053b1sup3.hkl ] Contains datablock boeh42

	Structure factor file (CIF format) (153.5 kbytes) [ doi:10.1107/S0108270106011243/av30053b2sup4.hkl ] Contains datablock boeh48

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