Cobalt-Functionalized Open-[60]Fullerenes

Redox noninnocent ligands have drawn considerable attention
owing
to effective interplay with metal(s) via π–d interactions,
enabling magnetic on/off switching as well as redox-controlled catalytic
reactions. Herein, we showcase the synthesis of [Co]2 and
[Co]1 complexes bearing open-[60]fullerene ligands, whose
absorption edges reached 1000 and 1500 nm, respectively. During the
reaction, o-dichlorobenzene (solvent) was partly
transformed to 2-chlorophenol, with which the Co complexes are most
likely to participate in a reductive elimination step. While [Co]2 contains a Co–Co bond identifiable by hybridized dz2 orbitals, [Co]1 possesses a fulvene-conjugated
open-[60]fullerene ligand which was generated by a ring-opening metathesis.
Theoretical calculations suggested that [Co]1 shows characteristic
redox behavior where the ligand works as an electron reservoir.