Hydrogen bonds. Part I. The ethynyl–H⋯O interaction in crystals of propargyl 2-bromo-3-nitrobenzoate
- 1 January 1966
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society B: Physical Organic
- p. 1235-1241
- https://doi.org/10.1039/j29660001235
Abstract
Propargyl 2-bromo-3-nitrobenzoate crystals are monoclinic, space group P21, with two molecules of the ester in a unit cell of dimensions a= 4·07, b= 17·99, c= 7·24 Å, β= 91° 30′. The atomic parameters were adjusted by Fourier and least-squares methods and the final discrepancy R over 951 independent reflexions is 6·5%. In the crystal there is an intermolecular H(ethynyl)O(carbonyl) distance of 2·39 Å and the C–HO angle is 156°. When the ester is in dilute solution in carbon tetrachloride the C–H stretching frequency of the ethynyl group is at 3313 cm.–1. The absorption shifts to 3262 cm.–1 when ethyl acetate is added to the solution, and to 3200 cm.–1 when dimethyl sulphoxide, a stronger proton acceptor, is added. In the solid state the acetylenic C–H stretch appears at 3266 cm–1.Keywords
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