A. Irving, H. Irving
Apr 1, 1987
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0
Influential Citations
4
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Journal
Journal of Crystallographic and Spectroscopic Research
Abstract
The 6-methylsulfonate (I) and the 6-carboxylic acid (II) of 2,4-bis(trichloromethyl)-1,3-benzdioxin both crystallize in the space groupP21/n withZ=4. Unit cell parameters of I are:a=13.398(7),b=14.553(2),c=8.945(2) Å, β=99.16(2)°; those of II are:a=6.010(16),b=25.741(16),c=10.505(10) Å, β=100.05(16)°. The structures were solved by direct methods and refined by full-matrix least squares, from room-temperature data obtained with an Enraf-Nonius CAD4 diffractometer, to conventionalR factors of 0.035 for I and 0.041 for II. The methylsulfonate group of I is disordered except for the sulfur atom and in II, which forms hydrogen-bonded dimers through the −COOH group, the hydrogen atom of the −COOH group is distributed equally between two positions.The conformation and molecular parameters of the 2,4-bis(trichioromethyl)-1,3-benzdioxin fragment for both compounds is very similar to that in 6-nitro-2,4-bis(trichloromethyl)-1,3-benzdioxin (Irving A., and Irving H. M. N. H. (1986)J. Cryst. Spectrosc. Res.16, 703). The dioxin ring has an approximate envelope conformation with a pseudoequatorial −CCl3 group in the 2-position and a pseudoaxial −CC13 group in the 4-position. C(ring)-Ceq(Cl3) is 1.525(5) Å for I and 1.536(6) Å for II, whereas the C(ring)-Cax(Cl3) bond length is 1.547(5) Å for I and 1.550(4) Å for II. The chemical shifts of the two protons in the heterocyclic ring do not appear to be altered by these changes in the 6-substituent.