Organophosphorus zwitterions are one of the most important but elusive intermediates for carbon-carbon bond formation in synthetic chemistry and biology. However, a lack of isolated examples due to their lability has hampered in-depth understanding of structures and their reaction mechanisms. In this study, we crystallographically reveal the solid-state structure of a phosha-Michael adduct engaged in a cage-opened C 60 skeleton, which is formed as a kinetic product. This compound exhibits dark brown colour in solution with an intense absorption band that extends to 1000 nm, reflecting intramolecular charge transfer transitions. From the 1,2-dicarbonyl moiety on the conjugated orifice, β-oxo-phosphorus ylide is formed as a thermodynamic product. The reaction mechanism that has long been disputed is examined by experimental and theoretical studies, showing a pathway which includes an S N 2 reaction as a key step instead of the hitherto considered carbene pathway.

The replacement of a ketone with a sulfide moiety changes the electronic properties of cage-opened fullerene ylides, thus causing a hypsochromic shift in absorption and a cathodic shift of reduction potentials.

The optical resolution of open-[60]­fullerenes has been limited to only one example since 1998, while the recent advances revealed the excellence of fullerenes as revisited chiral functional materials. Different from conventional chiral induction on [60]­fullerene by a multiple-functionalization, a random disruption of the spherical π-conjugation is avoidable for open-[60]­fullerenes. Moreover, the macrocyclic orifices enable a metal coordination which endows modulated electronic structures on chiral chromophores. Herein, we showcase Li+-coordination behavior and optical resolution of three chiral open-[60]­fullerene ligands, showing a giant dissymmetry factor up to 0.20 owing to a congenital topology of the spherical π-conjugation.