Synthesis, characterization and properties of new organocobalt complexes containing η5-functionally substituted cyclopentadienyl and [60]fullerene ligands

The organocobalt complexes containing functionally substituted cyclopentadienyl ligands (η5-RC5H4)Co(PPh3)2 (1a, R=EtO2C; 1b, R=MeCO) were synthesized by reactions of the corresponding functionalized cyclopentadienides RC5H4Na with (PPh3)3CoCl in 65 and 85% yields, respectively. The ligand exchange reaction of 1a with PhCCPh afforded (η5-EtO2CC5H4)Co(PPh3)( η2-PhCCPh) (2a) in 72% yield, whereas (η5-RC5H4)Co(PPh3)2 (1a, R=EtO2C; 1b, R=MeCO; 1c, R=H) reacted with C60 through ligand exchange to give (η5-RC5H4)Co(PPh3)(η2-C60) (3a, R=EtO2C; 3b, R=MeCO; 3c, R=H) in 34–68% yields. 3a could be also obtained similarly by ligand exchange reaction of 2a with C60 in 83% yield. In addition, reaction of 2a or 3a with excess iodine I2 produced (η5-EtO2CC5H4)Co(PPh3)(I)2 (4a) in 90–91% yields. The new compounds 1a, 1b, 2a, 3a–3c and 4a were characterized by 1H-NMR, 31P-NMR, IR, UV–Vis spectra and elemental analysis, whereas the reverse saturable absorption properties of the organocobalt fullerene complexes 3a and 3c along with C60 were studied by Z-scan method.