[Arene . Me3C+] non-Covalent Complexes in the Gas Phase (Trifluoro)methylation of Tertbutyl-substituted Diphenylalkanes.”

The reaction of Me2F+, Me2Cl+ and CF3+ with p-Me3CC6H4(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 Me3C loss following CX3- (X = H, F) addition to the tert-butyl-substituted ring is significantly reduced with respect to a single-ring model substrate, p-Me3CC6H4Me. [Arene · Me3C+] non-covalent complexes mediate the observed interannular and intermolecular Me3C+ transfer. Unimolecular cleavage of Me3CH from [arene · Me3C+], 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.