C vs N: which end of the cyanide anion is a better hydrogen bond acceptor?
The ability of the C and N ends of the cyanide anion (CN(-)) as acceptors of hydrogen bonds, an experimentally difficult problem, has been computationally examined in this study. Structures obtained in our previous work involving cyanide binding within the cavity of a triazolophane macrocycle (Chem.-Eur. J. 2011, 17, 9123-9129) were used to analyze the problem. Three different approaches involving (a) breakdown of the triazolophane into smaller components, (b) population analyses, and (c) ion-dipole analyses helped demonstrate that the N terminus of cyanide is a slightly better hydrogen bond acceptor than the C terminus even though it is not the site of protonation or covalent bond formation. This outcome reflects a competition between the preference for noncovalent interactions at the nitrogen and covalent bond formation at the carbon.
Department of Chemistry, Indiana University , Bloomington, Indiana 47405, United States.
Raghunath O
RO
Ramabhadran
Yuran
Y
Hua
Amar H
AH
Flood
Krishnan
K
Raghavachari
D000838:Anions / Q000737:chemistry*; D003198:Computer Simulation; D003486:Cyanides / Q000737:chemistry*; D006860:Hydrogen Bonding; D008956:Models, Chemical; D011522:Protons; D055672:Static Electricity
D000838:Anions; D003486:Cyanides; D011522:Protons