Density functional study of carbon-carbon bond activation in curved polyaromatic hydrocarbons by transition-metal complexes

Density functional calculations have been performed on the oxidative addition of a Pt(0) fragment, Pt(PH3)(2), to one of the rim C-C bonds of semibuckminsterfullerene (C30H12), to give an eta(2)-sigma-bonded Pt(II)-buckybowl complex. To evaluate the effect of the ring strain and of the hydrocarbon curvature on the C-C bond activation, analogous calculations have been performed on the oxidative addition of Pt(0) to the C-C bond in five-membered rings of less strained hydrocarbons, such as dihydro-3-fluorene (C13H10) and benzo[ghi]fluoranthene (C18H10). The optimized geometries of the eta(2)-sigma-bonded Pt(II) buckybowl and dihydroanthracene complexes have been found to be in good agreement with the X-ray experimental data. Reliable values have been calculated for the energy of the Pt(0) oxidative addition to these hydrocarbons and compared with the corresponding energies of the C-C bond cleavage, allowing us to distinguish between strain energy within the five-membered ring and strain energy associated with the bowl-like curvature.