Dichlorocarbene addition to C60 from the trichloromethyl anion: carbene mechanism or Bingel mechanism?

The reactions of C(60) and trichloromethyl anion (CCl(3)(-)) via both the Bingel mechanism and the carbene mechanism were comparably studied by means of density functional theory (DFT) computations. The Bingel mechanism is highly competitive as compared with the carbene mechanism that leads to the formation of C(60)(CCl(2)). Unlike the carbene mechanism with a weak regioselectivity and solvent sensitivity, the Bingel mechanism yields the [6,6]-C(60)(CCl(2)) isomer as the exclusive product and favors highly polar solvents. The results receive strong experimental support and simultaneously rationalize these experimental findings.