Norbornadiene functionalized triaza-triangulenium and trioxa­-triangelium platforms

Triazatriangulenium (TATA) and trioxatriangulenium (TOTA) ions are among the most efficient systems to mount functional molecules onto atomically flat surfaces such as Au(111). The TATA and TOTA units serve as platforms that absorb onto the surface and form ordered monolayers, while the functional groups are protruding upright and freestanding from the central carbon atoms. Azobenzene derivatized TATA’s are known to exhibit extremely fast cis → trans isomerizations on metal surfaces, via a peculiar non-adiabatic singlet→triplet→singlet mechanism. We now prepared norbornadienes (NBD) and quadricyclanes (QC) attached to TATA and TOTA platforms to check if these accelerated rates and the spin change mechanism also apply to [2+2]cycloreversions (QC→NBD).