Crystal structure of (fluorosulfonyl)fluoroacetic acid: A novel four-center hydrogen-bond system involving a C-H donor

The crystal structure of FSO2CFHCOOH has been determined by a single-crystal X-ray study. The crystals are monoclinic, of space group P2(1)/c, and have the following cell parameters: a = 5.0164(6) Angstrom, b = 9.658(2) Angstrom, c = 11.061(2) Angstrom, beta = 90.54(1)degrees, Z = 4. The carboxyl groups of the molecules form the usual hydrogen-bonded, centrosymmetric dimers, but each molecule also interacts with three other neighboring molecules by hydrogen bonds from the methine hydrogen to two sulfonyl oxygens and to a carbonyl oxygen, making a four-center system. The extensive network of hydrogen bonding in this material appears to be responsible for its existence as a solid. This material has also been characterized by H-1, C-13, and F-19 NMR, IR, and mass spectroscopy.