Crystal Structure of (Fluorosulfonyl)fluoroacetic Acid:  A Novel Four-Center Hydrogen-Bond System Involving a C−H Donor

Abstract

The crystal structure of FSO 2 CFHCOOH 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) Å, b ) 9.658(2) Å, c ) 11.061(2) Å, ) 90.54(1)°, 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.

Synthesis of Poly- and the First Perfluoroalkyl-N(SO2F)2Derivatives: Improved Methods for the Preparation of XN(SO2F)2(X = H, Cl) and Single-Crystal Diffraction Studies of HN(SO2Cl)2, HN(SO2F)2, and CF3CH2N(SO2F)2

“…However, the other two crystallographically independent molecules that are present are linked via bifurcated intermolecular hydrogen bonds, forming a fourmembered center. This type of bifurcated hydrogen bonding originating from an alkyl proton has recently been reported by Gard et al 47 Figure 7 shows intermolecular hydrogen-bonding networks resulting from the interaction of the molecules from different unit cells. These distances range from 2.43(3) to 2.89- (3) Å as seen in Table 6.…”

Selective Reactivity of the Phosphorus−Chlorine and Carbon−Chlorine Bonds in Cyclic Chlorocarbaphosphazenes: An Unusual Activation of a Carbon−Nitrogen Bond in Trialkylamines

“…In addition, there are two more long-range interactions: H1A···O3 b = 2.436 Å (b = 1 − x , − 1 / 2 + y , 1 / 2 − z ) and H1A···N2 b = 2.503 Å (Figure b). The participation of an alkyl proton in fluoroalkyl compounds in the formation of multicentered hydrogen bonding has recently been reported …”

Studies on the Reactivity of Tetrafluoro- and Pentafluorophenyl Trimethylsilyl Ether with Pentafluorobenzenes. Chemistry and X-ray Structural Investigations of Polyfluorodiphenyl Ethers

“…The short distance of the intermolecular hydrogen−oxygen bonds in 17 and 18 is unique, as these values lie around 2.6 Å for fluorinated carboxylic acids (C 6 F 5 COOH; CF 3 COOH ). A much shorter value of 1.91(7) Å has been reported recently for (fluorosulfonyl)fluoroacetic acid 10 Crystal packing diagram of HC 6 F 4 OC 6 F 4 COOH ( 17 ), along the a -axis showing dimer formation with intermolecular H···O and H···F interactions.

11 Dimeric structure of C 6 F 5 OC 6 F 4 COOH ( 18 ).

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