Nickel sandwich complex / Voltammetry, cyclic / Electrochemistry / Reductive dimerization / ESR spectra
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Reduction of (Cyclobutadiene)(cyclopentadienyl)- and (1,5-Cyclooctadiene)(cyclopentadienyl)nickel CationsCyclic voltammetry of the four cationic Ni sandwich complexes [Ni(C5R5)(C4R4')]+ (2: R = H, R' = Ph; 3: R = H, R' = Me; 4; R = Me, R' = Ph; 5: R = R' = Me) shows reversible one-electron reductions for the phenyl derivatives 2 and 4 and a peak pattern characteristic of reductive dimerization/oxidative monomerization for the methyl derivatives 3 and 5. The product of the reduction of 3 was isolated and characterized analytically and by an X-ray structure determination as the dimer 6 of 3, linked through cyclobutenyl rings, the first example for a dimerization of an electron-rich sandwich complex at a substituted C atom. EPR spectra of the neutral complexes 2 and 4 are compared to those of (1,5-cyclooctadiene)(cyclopentadienyl)nickel (7) and are interpreted in terms of a substantial static Jahn-Teller distortion.
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