Web Release Date: May 31,
From Sulfoxide Precursors to Model Oligomers of Conducting Polymers
Contribution from the Limburgs Universitair Centrum, Institute for Materials Science (IMO), Department SBG, Universitaire Campus, B-3590 Diepenbeek, Belgium
Received December 13, 2001
Abstract:
The gas-phase internal elimination (Ei) reaction of the sulfoxide (-SO-CH3) precursors of ethylene
and model oligomers of PPV and PITN has been investigated by means of Hartree-Fock, M
ller-Plesset
(second and fourth order), and Density Functional Theory (B3LYP, MPW1K) calculations. Considerable
differences between the obtained ground state and transition state geometries and the calculated activation
energies are observed from one approach to the other, justifying first a careful calibration against the results
of a benchmark CCSD(T) study of the Ei reaction leading to ethylene. In comparison with the CCSD(T)
results, as well as with available experimental data, DFT calculations along with the MPW1K functional
are found to be a very appropriate choice for describing the Ei pathway. The leading conformations of the
precursors, the relevant transition state structures, and the energy barriers encountered along the lowest
energy path to unsubstituted, 
and 
chloro-, methoxy-, and cyano-substituted ethylene, styrene, stilbene
in its cis and trans forms, and at last trans-biisothianaphthene have therefore been identified and
characterized in detail employing DFT (MPW1K). Depending on the substituents attached to the C and
C atoms, different reaction mechanisms are observed.
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