Substituent Effects and the Charge Topology in Nitriles and Cyanides

Abstract:

In order to study the substituem effects and the bonding of the C≡N group, a SCF 4–31G ab initio calculation was undertaken for the C≡N” ion, for nitriles with R = H, F, HO, FO, H3C, HC≡C, NH2, O=N, N3, C≡N, the E and Z form of iminoacetonitrile and for cyanides with R = Li, HBe, and B. The electron density p(r) was analyzed by means of the topological theory of atoms in molecules. The surfaces of zero-flux in ∇ρ(r) showed that the C valence density of the target fragment absorbed most of the changes, while the N was only slightly perturbed by the R-C bond formation. A correlation was found between the position of the bond critical point and the electronegativity of R for R-C in nitriles but not for the C≡N bond. This difference was explained by the changes in the strength of the substituent fields acting on both bonds. The ∇2ρ(r) distribution in the C≡N group for the different substituents and counterions showed that all the bonded and nonbonded local concentrations present in the C and N valence shells were affected in a complex way by the bond formation. © 1991, American Chemical Society. All rights reserved.

Año de publicación:

1991

Keywords:

Fuente:

scopus