ja012700p_si_001.pdf (76.17 kB)
From Sulfoxide Precursors to Model Oligomers of Conducting Polymers
journal contribution
posted on 2002-05-31, 00:00 authored by Luc Claes, Jean-Pierre François, Michael Simon DeleuzeThe 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, Møller−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, α and β 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 Cα and
Cβ atoms, different reaction mechanisms are observed.