Anomalous Energy Effects in some Aliphatic and Alicyclic Aza Systems and their Nitro Derivatives
Abstract
We have used an ab initio Self Consistent Field (SCF) molecular orbital approach in conjunction with the isodesmic reaction procedure to investigate anomalous energy effects in aliphatic and alicyclic aza systems. These molecules are found to be significantly stabilized, which we attribute to sigma-conjugation of the nitrogen lone pairs; these are presumably delocalized to some extent through the sigma-bond framework. The stabilization increases with the number of nitrogens in a series of similar molecules and is greater in cyclic systems, particularly when rings are fused. The magnitudes of the most negative electrostatic potentials of the aza nitrogens, which can be viewed as indicating the degrees of delocalization of the nitrogen lone pairs, decrease as the added stability increases. In these systems, the introduction of nitro groups also has an overall stabilizing effect, which may be due to further delocalization of sigma-electrons, reflecting the strong electron-withdrawing power of the nitro group. (KT)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1990
- Accession Number
- ADA221145
Entities
People
- Jane S. Murray
- Jorge M. Seminario
- Paul C. Redfern
- Peter Politzer
Organizations
- University of New Orleans