More On H-Bonding

After C&EN‘s recent coverage (Sept. 22, page 10) of our work on “antielectrostatic H-bonding” (Angew. Chem. Int. Ed. 2014, DOI: 10.1002/ange.201405812), we were kindly informed by professors Ibon Alkorta of Madrid, Spain, and Steven R. Kass of Minneapolis of earlier experimental (1, 2) and theoretical (3, 4) works pertaining to doubly ionic H-bonded species in the gas phase that are peripherally related to our work.

These works involve somewhat different species (such as large peptide clusters) and different theoretical focus than the central “What is H-bonding?” question of our work. They should, however, be recognized (along with crystallographic evidence on bicarbonate dimer [5] previously noted) as relevant to attempted experimental and theoretical detection and characterization of paradoxical “antielectrostatic” (or “electrostatics-defying” [3]) H-bond species that challenge current empirical modeling and pedagogy.

1. S. W. Lee, J. L. Beauchamp, J. Am. Soc. Mass Spectrom. 1999,10, 347.

2. L. Feketeova, R. A. J. O’Hair, Chem. Commun. 2008, 4942.

3. S. R. Kass, J. Am. Chem. Soc. 2005, 127, 13098; A. Shokri, M. Ramezani, A. Fattahi, S. R. Kass, J. Phys. Chem. A 2013, 117, 9252.

4. I. Mata, I. Alkorta, E. Molins, E. Espinosa, ChemPhysChem 2012,13, 1421.

5. D. Braga, F. Grepioni, J. J. Novoa, Chem. Commun. 1998, 1959. See also ensuing discussions: T. Steiner, Chem. Commun. 1999, 2299; M. Mascal, C. E. Marjo, A. J. Blake, Chem. Commun. 2000, 1591; and P. Macchi, B. B. Iversen, A. Sironi, B. C. Chakoumakos, F. K. Larsen, Angew. Chem. Int. Ed. 2000,39, 2719.

Frank Weinhold
Roger A. Klein
Madison, Wis.