The accurate C2v phenonium and benzenonium ion structures confirmed by correlated GIAO-MP2 NMR chemical shift calculations

Abstract

Cram presented the first evidence for the intermediacy of phenonium ions in the solvolysis of 8-arylalkyl halides in 1949.'~~

Persistent Bissilylated Arenium Ions

“…DFT‐based methods like GIAO/DFT calculations are known to overestimate paramagnetic contributions to the chemical shielding, giving, in critical cases, overly deshielded chemical shifts 58a, 59. In a series of papers Gauss, Siehl, and Schleyer and co‐workers60–63 have demonstrated the importance of including electron correlation in chemical shift calculations for unsaturated carbocations like vinyl,61 allyl,62 and arenium14, 63 ions. For these cations, MP214, 19, 62, 63 or even higher correlated methods like CCSD(T)61 must be applied.…”

Comparison of density functional theory models' ability to reproduce experimental13C-NMR shielding values

“…Tserves several useful purposes: it helps to determine the structures of molecules in solutions, 1 it provides a test of theoretical models via a comparison with the experimental data, and the results…”

The Gas-Phase Reactivity ofp-Me3Si-Substituted 1,3-Diphenylpropane Towards Charged Electrophiles: Intra- and Interannular Hydrogen Migrations

“…700 Torr of bulk gas (CH 4 or MeCl) in the presence of 10 Torr of O 2 as a radical scavenger. The absolute radiolytic yields of the products account for a major portion of the primary reactant ions formed by the ionization of the bulk gas and ensuing ion ± molecule reactions.…”

“…A related interannular hydrogen migration takes place following electrophilic substitution of a,w-diphenylalkanes, [2] along pathways whose gasphase kinetics have been the topic of several experimental [2,3] and theoretical investigations. [4] Mass-spectrometric investigations have revealed extensive hydrogen scrambling in protonated a,w-diphenylalkanes that may lead to complete equilibration in the 10 msec time frame, typical of metastable loss of benzene.…”