Conference paper

Why are the Properties of Polycyclic Hydrocarbons Additive over Conjugation Circuits?

J. A. N. F. Gomes ; Departamento de Quimica, Faculdade de Ciencias, 4000 PORTO, Portugal

Abstract

Properties as different as resonance energies and magnetic
ring-currents are investigated and a non-empirical system of increments
is proposed. It is shown that the :n:-electron properties of ·
conjugated, polycyclic hydrocarbons are additive over all conjugation
circuits that can be identified in the molecule. The contribution
from each individual conjugation circuit is calculated non-empirically
on a simple, free-electron model for the associated annulene.
Within a special form of the resonance theory, it is shown that
all conjugation circuits should contribute with equal weight, and
not only the »independent circuits« as proposed earlier by Randie
or certain lower circuits as postulated by Herndon. Contributions
from higher circuits turn out quite naturally, however, to be small.
Results for a wide variety of polycyclic hydrocarbons, alternant
and non-alternant, are presented. Both for resonance energies
and for magnetically-induced ring-currents, very satisfactory agreement
with conventional calculations has been obtained.

Keywords

Hrčak ID:

194459

URI

https://hrcak.srce.hr/194459

Publication date:

25.1.1981.

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