Redox Chemistry of Nickelocene-Based Monomers and Polymers
journal contribution
posted on 2021-06-18, 13:04 authored by Rebecca A. Musgrave, Andrew D. Russell, Paul R. Gamm, Rebekah L. N. Hailes, Kevin Lam, Hazel
A. Sparkes, Jennifer C. Green, William E. Geiger, Ian MannersThe
oxidation of [n]nickelocenophanes [Ni(η5-C5H4)2(CH2)3] (3), [Ni(η5-C5H4)2(SiMe2)2] (10), [Ni(η5-C5H4)2(SiMe2)2O] (11), [Ni(η5-C5H4)2(CH2)4] (12), and poly(nickelocenylpropylene) [Ni(η5-C5H4)2(CH2)3]n (4) to both the
monocationic and dicationic species was investigated in dichloromethane
by cyclic voltammetry (CV) and square-wave voltammetry. The presence
of acetonitrile on the oxidation potentials of 3 in dichloromethane
was also investigated by CV. The [n]nickelocenophanes 3 and 10–12 exhibited
two single-electron Nernstian redox
processes, and the monocations [3]+, [10]+, [11]+, and [12]+ were isolable as [B(C6F5)4]− salts after chemical oxidation, and were structurally
characterized. Ni–Cpcent distances in all four monomers
decreased upon oxidation, with a structural distortion manifested
in the ring-tilt angle, α, among other angles. CV studies of
the reversible first oxidation process to the polyelectrolyte {[Ni(η5-C5H4)2(CH2)3]+}n ([4]n+) were used to estimate
the molecular weight of the polymeric material (Mw = 5300 g mol–1) by comparing its diffusion
coefficient with that of a monomeric analogue, and the second electrochemical
oxidation of polymer 4 was found to be only partially
chemically reversible.
