The dicyanometacyclophanediene
1 is diprotonated at the cyano groups (
1H22+) in various superacidmedia. Upon quenching, intact
1 and the ring-closed CPD
2 were obtained in a 3:2 or 3:1 ratio, dependingon the superacid system. Compound
2 undergoes ring opening in the superacid to give the
ipso-monoprotonated
2H+, which on quenching furnishes 1-cyanopyrene as a major product together with
2and
1. The dication
32+, with strongly deshielded internal methyls, was generated from the epoxyannulene
3. Ketones
4-
6 and ester
7 are O/C diprotonated to give paratropic carboxonium-annulenium dications(
4H22+,
5H22+,
6H22+, and
7H22+, respectively). Ester
8 gives a trication by two-electron oxidation andO-protonation. Conjugated carboxylic acid
9 gives a mixture of two dications by CO and ring protonation.The dibromo derivatives
10 and
11 form carboxonium ions, whereas the monobromo derivative
12 isO/C diprotonated to give an oxonium-annulenium dication. Charge delocalization modes and tropicityin the resulting species are evaluated by NMR and GIAO-DFT. Facile formation of
2 from
1 in quenchingexperiments indicates that thermal closing can be achieved with the diprotonated dinitrile, without imposingskeletal rearrangement.
