[ARENE-CENTER-DOT-ME(3)C(+)] NONCOVALENT COMPLEXES IN THE GAS-PHASE (TRIFLUORO)METHYLATION OF TERT-BUTYL-SUBSTITUTED DIPHENYLALKANES

The reaction of Me(2)F(+), Me(2)Cl(+) and CF3+ with p-Me(3)CC(6)H(4)(CH2)(n)C6D5(n = 2, 3) initiates a reaction pattern whose major features are accounted for by the additional electrostatic stabilization afforded by the second (spectator) aromatic ring on ionic intermediates and ion-molecule complexes, The Me(3)C loss following CX(3)(+)(X, = H,F) addition to the tert-butyl-substituted ring is significantly reduced with respect to a single-ring model substrate, p-Me(3)CC(6)H(4)Me. [Arene . Me(3)C(+)] non-covalent complexes mediate the observed interannular and intermolecular Me(3)C(+) transfer. Unimolecular cleavage of Me(3)CH from [arene . Me(3)C(+)], following side-chain H- abstraction, a major fragmentation pathway under mass spectrometric conditions, is instead largely inhibited in the reported radiolytic experiments. Such behavior is accounted for by the effective stabilization of ion-molecule non-covalent complexes ensured by unreactive collisions with about 1 atm bath gas.