S S symmetry Article NMR Properties of the Cyanide Anion, a Quasisymmetric Two-Faced Hydrogen Bonding Acceptor Ilya G. Shenderovich 1,2,* and Gleb S. Denisov 2 1 Institute of Organic Chemistry, University of Regensburg, Universitaetstrasse 31, 93053 Regensburg, Germany 2 Department of Physics, St. Petersburg State University, 198504 St. Petersburg, Russia;
[email protected] * Correspondence:
[email protected] Abstract: The isotopically enriched cyanide anion, (13C≡15N)−, has a great potential as the NMR probe of non-covalent interactions. However, hydrogen cyanide is highly toxic and can decompose explosively. It is therefore desirable to be able to theoretically estimate any valuable results of certain experiments in advance in order to carry out experimental studies only for the most suitable molecular systems. We report the effect of hydrogen bonding on NMR properties of 15N≡13CH···X and 13C≡15NH···X hydrogen bonding complexes in solution, where X = 19F, 15N, and O=31P, calculated at the !B97XD/def2tzvp and the polarizable continuum model (PCM) approximations. In many cases, the isotropic 13C and 15N chemical shieldings of the cyanide anion are not the most informative NMR properties of such complexes. Instead, the anisotropy of these chemical shieldings and the values of scalar coupling constants, including those across hydrogen bonds, can be used to characterize the geometry of such complexes in solids and solutions. 1J(15N13C) strongly correlates with the length of the N≡C bond. Keywords: cyanide; hydrogen bonding; non-covalent interactions; NMR; chemical shift anisotropy; scalar coupling; DFT; GIAO Citation: Shenderovich, I.G.; Denisov, G.S. NMR Properties of the Cyanide Anion, a Quasisymmetric Two-Faced Hydrogen Bonding 1.