Unusual hydrogen bonding in L-cysteine hydrogen fluoride

V. S. Minkov, V. V. Ghazaryan, E. V. Boldyreva, A. M. Petrosyan

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


L-Cysteine hydrogen fluoride, or bis(l-cysteinium) difluoride-L-cysteine-hydrogen fluoride (1/1/1), 2C3H8NO2S+·2F-·C3H7NO2S·HF or L-Cys+(L-Cys⋯L-Cys+)F-(F-⋯H - F), provides the first example of a structure with cations of the 'triglycine sulfate' type, i.e. A+(A⋯A+) (where A and A+ are the zwitterionic and cationic states of an amino acid, respectively), without a doubly charged counter-ion. The salt crystallizes in the monoclinic system with the space group P21. The dimeric (L-Cys⋯L-Cys+) cation and the dimeric (F-⋯H - F) anion are formed via strong O - H⋯O or F - H⋯F hydrogen bonds, respectively, with very short O⋯O [2.4438 (19) Å] and F⋯F distances [2.2676 (17) Å]. The F⋯F distance is significantly shorter than in solid hydrogen fluoride. Additionally, there is another very short hydrogen bond, of O - H⋯F type, formed by a L-cysteinium cation and a fluoride ion. The corresponding O⋯F distance of 2.3412 (19) Å seems to be the shortest among O - H⋯F and F - H⋯O hydrogen bonds known to date. The single-crystal X-ray diffraction study was complemented by IR spectroscopy. Of special interest was the spectral region of vibrations related to the above-mentioned hydrogen bonds.

Original languageEnglish
Pages (from-to)733-741
Number of pages9
JournalActa Crystallographica Section C: Structural Chemistry
Publication statusPublished - 1 Aug 2015


  • amino acid salt
  • bond/angle distribution
  • crystal structure
  • dimeric cation
  • IR spectroscopy
  • L-cysteine hydrogen fluoride
  • short hydrogen bonds


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