INVESTIGADORES
VERA Domingo Mariano Adolfo
artículos
Título:
A theoretical approach to understanding the fragmentation reaction of halonitrobenzene radical anions
Autor/es:
A B PIERINI; J S DUCA; D M A VERA
Revista:
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2
Editorial:
Royal Society of Chemistry
Referencias:
Lugar: London; Año: 1999 p. 1003 - 1010
ISSN:
0300-9580
Resumen:
We present a semiempirical AM1 study of the radical anions of o-, m- and p-halonitrobenzenes and some alkyl substituted derivatives in relation to their orbital isomerism and the energy of their interconversion (E).
Halobenzene radical anions are also included for comparison. The
results obtained with the RHF/CI(5) formalism account for the
differences observed in the fragmentation rate of these radical anions
under thermal and photochemical conditions. Based on the calculated E the intramolecular thermal electron transfer from the system to the *
CX bond involved in the fragmentation of the intermediates into an
aromatic radical and the anion of the leaving group occurs with
considerable energy for the p-, m- and o-chloronitrobenzenes (1ac) and the p- and m-bromo
(2a, b) derivatives. The fragmentation of these radical anions is
favoured either from the first or from higher energy excited doublet
states. On the other hand, the intramolecular thermal electron transfer
is favoured for the p-, m-, o-iodo (3ac) and o-bromo
(2c) derivatives. The results obtained for some alkyl substituted
halonitrobenzene radical anions are in agreement with their known
experimental fragmentation rates.