Syntheses, Structure, and Derivatization of Potassium Complexes of Penta(organo)[60]fullerene-Monoanion, -Dianion, and -Trianion into Hepta- and Octa(organo)fullerenes

Two-electron reduction of penta(organo)[60]fullerenes C60Ar5H (Ar = Ph and biphenyl) by
potassium/mercury amalgam afforded potassium complexes of the corresponding open-shell radical dianions
[K+(thf)n]2[C60Ar52-•]. These compounds were characterized by UV−visible-near-IR and electron spin
resonance spectroscopy in solution. Anaerobic crystallization of [K+(thf)n]2[C60(biphenyl)52-•] that exists largely
as a monomer in solution gave black crystals of its dimer [K+(thf)3]4[(biphenyl)5C60−C60(biphenyl)54-],
in which the two fullerene units are connected by a C−C single bond [1.577(11) Å] as determined by X-ray diffraction. Three-electron reduction of C60Ar5H with metallic potassium gave a black−green trianion [K+(thf)n]3[C60Ar53-]. The reaction of the trianion with an alkyl halide RBr (R = PhCH2 and
Ph2CH) regioselectively afforded a hepta-organofullerene C60Ar5R2H, from which a potassium complex
[K+(thf)n][C60(biphenyl)5(CH2Ph)2-] and a palladium complex Pd[C60(biphenyl)5(CH2Ph)2](π-methallyl) as well
as octa-organofullerene compounds C60(biphenyl)5(CH2Ph)3H2 and Ru[C60(biphenyl)5(CH2Ph)3H]Cp were
synthesized. These compounds possess a dibenzo-fused corannulene π-electron conjugated system and
are luminescent.