Electrochemical Behavior of Bis(cyclopentadienylnickel)−Alkyne Derivatives

• Published in: Organometallics 1997-02, Vol.16 (4), p.695-700
• Main Authors: Osella, Domenico, Rossetti, Rosanna, Nervi, Carlo, Ravera, Mauro, Moretta, Marcella, Fiedler, Jan, Pospísil, Lubomir, Samuel, Edmond
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om960270j

The electrochemical behavior of dimetallic [Ni2Cp2](RC⋮CR‘) (Cp = π-cyclopentadienyl; R = R‘ = Ph; COOMe; R = H, R‘ = Ph; R= Me, R‘ = Ph; R = Ph, R‘ = −C⋮CPh) and tetrametallic M2M2‘(PhC⋮CC⋮CPh) (M2 = M2‘ = Ni2Cp2; M2 = Ni2Cp2, M2‘ = Co2(CO)6) derivatives has been investigated. All dinickel compounds undergo an electrochemically and chemically reversible 1e (metal-centered) reduction followed by further ligand-based reductions. The tetrametallic complex [Ni2Cp2]2(PhC⋮CC⋮CPh) shows two fully reversible 1e (metal-centered) reductions, indicating a strong electronic communication between the two redox units (ΔE° = 670 mV). The mixed-metal [Ni2Cp2][Co2(CO)6](PhC⋮CC⋮CPh) derivative exhibits a 1e (Co2-centered) reduction at first, followed by a further 1e (Ni2-centered) reduction; such an electrochemical scenario is complicated by a fast decomposition following the first reduction, which produces some amount of [Ni2Cp2](PhC⋮CC⋮CPh) compound, having a dangling (uncoordinated) triple bond.