2,6-Dimethylmesitylene-2,6-diyl Dication, a Unique Dienyl-Allyl Dication and Its Comparison with Bisallylic Benzene Dication1

摘要

In conclusion, we have succeeded in the preparation and characteriziation of the first persistent (stable) dienyl-allyl dication, the 2, 6-dimethylmesitylene-2, 6-diyl dication 2, and study its structure by ~1H and ~13C NMR spectroscopies. DFT/ IGLO theoretical NMR chemical shift calculations gave excel- lent correlation with the experimental data. The combined experimental and theoretical approach support structure 2a wherein the dienyl and allylic cation units are insulated from each other not unlike what is theoretically calculated for the related benzene dication 3.