Synthesis reactivity and electrochemical properties of substituted cyclopentadienyl cobalt (III) complexes

Cyclopentadienyl cobalt complexes (η5-C5H4R) CoLI2 [L = CO,R=-COOCH2CH=CH2 (3); L=PPh3, R=-COOCH2-CH=CH2 (6); L=P(p-C6H4O3)3, R = -COOC(CH3) = CH2 (7), -COOCH2C6H5 (8), -COOCH2CH = CH2 (9)] were prepared and characterized by elemental analyses, 1H NMR, ER and UV-vis spectra. The reaction of complexes (η5-C5H4R)CoLI2 [L= CO, R= -COOC(CH3) = CH2 (1), -COOCH2C6H5(2); L=PPh3, R=-COOC (CH3) = CH2 (4), -COOCH2C6H5 (5)] with Na-Hg resulted in the formation of their corresponding substituted cobaltocene (η5-C5H4R)2 Co[R=-COOC(CH3) = CH2 (10), -COOCH2C6H5 (11)]. The electrochemical properties of these complexes 1–11 were studied by cyclic voltammetry. It was found that as the ligand (L) of the cobalt (III) complexes changing from CO to PPh3 and P(p-tolyl)3, their oxidation potentials increased gradually. The cyclic voltammetry of α,α′-substituted cobaltocene showed reversible oxidation of one electron process.