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-center dot]. These compounds were characterized by UV-visible-near-IR and electron spin resonance spectroscopy in solution. Anaerobic crystallization of [K+(thf)(n)](2)[C-60(biphenyl)(5)(2-center dot)] that exists largely as a monomer in solution gave black crystals of its dimer [K+(thf)(3)](4)[(biphenyl)(5)C-60-C-60(biphenyl)(5)(4-)], in which the two fullerene units are connected by a C-C single bond [1.577(11) angstrom] as determined by Xray 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)][C-60(biphenyl)(5)(CH2Ph)(2)(-)] and a palladium complex Pd[C-60(biphenyl)(5)(CH2Ph)(2)](pi-methallyl) as well as octa-organofullerene compounds C-60(biphenyl)(5)(CH2Ph)(3)H-2 and Ru[C-60(biphenyl)(5)(CH2Ph)(3)H]Cp were synthesized. These compounds possess a dibenzo-fused corannulene pi-electron conjugated system and are luminescent.