Carbon-Carbon Bond Formation "Catalyzed" by Ion-Pair Constituents

Reported here is an ab initio modelling of C-C bonding in halocarbon molecules, with alkali-metal atoms attached. The studied systems feature metal-halide counterion pairs appearing along the way. Their electric field leads to a mutual attraction, as well as influences the process directly. Such a combination favours bonding of reactants over significantly reduced potential energy barriers. The process involves uncommon species including a counterintuitive isomer of a metal-halocarbon system bound via "collective" ionic bonds, an intermediate charge-transfer complex exhibiting an unusual hyper-coordinated carbon, and possible another (also uncommon) intermediate insertion complex with a molecule trapped between counterions. The overall reaction involves an "umbrella"-type inversion of bonds and recombination of framing metal-halide ion-pair around insert. The process could be tracked via IR spectra at all stages, from reactants through intermediates to products. This could enable experimental detection of relevant species formation, their differentiation, and monitoring overall system evolution.