Calculated Bonding in the Pseudohalide Anions and Their Hydracids

Abstract

The bond characters and energies of the nitrogen-containing pseudohalide anions, CN−, N3−, NCO−, NCS−, NCSe−, NCTe−, and their common hydracids, as well as some related isoelectronic systems, have been calculated using an internally consistent procedure based on the utilization of ``unsymmetrical group orbitals'' (LCGO method). Coulomb integrals are related to the valence-state electronegativities which are obtained by three different procedures. It is concluded that the results are more sensitive to the rate of change of the Coulomb integral with charge than to the value of the Coulomb integral itself. This LCGO—MO method greatly simplifies the calculations and gives results identical with the longer LCAO procedures which correlate well with the physical and chemical properties of the substances. The calculations account for the relative acid strengths and correlate quantitatively with the experimentally determined C–N stretching-force constants and 14N NMR chemical shifts.