Proton Transfers in Hydrogen Bonded Systems. 5. Analysis of Electronic Redistributions in (N2H7)+

Document Type

Article

Journal/Book Title

International Journal of Quantum Chemistry

Publication Date

1981

Publisher

Wiley

Volume

20

Issue

8

First Page

221

Last Page

229

Abstract

The transfer of the central proton between the two NH3 units of (H3NHNH3)+ is studied using the 4–31 G basis set within the ab-initio Hartree-Fock formalism. Electron density difference maps are constructed which clearly indicate electronic redistributions which accompany the half-transfer of the proton from its equilibrium position (NHN) to the midpoint of the hydrogen bond (NHN). The overall loss of electronic charge from the proton-accepting molecule originates in three distinct regions of space, while a density buildup of smaller magnitude is observed in a characteristic region centered about the N nucleus. Similar regions are noted for the proton-donating molecule, although the changes are reversed in sign. A partitioning of the total density changes into contributions from the various molecular orbitals demonstrates that the a1 orbitals are associated with density shifts along the H-bond axis. Changes in the N lone pairs are attributed chiefly to the (5a1,6a1) pair and are somewhat attenuated by opposite shifts involving the (3a1. 4a1) pair. Orbitals of e symmetry lead to polarizations of the NH bonds and density shifts perpendicular to the H-bond axis.

Comments

Originally published by Wiley-Blackwell in the International Journal of Quantum Chemistry.

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