Deprotonation of the aminocobaltocenium ion [Cc-NH2]+ ([H-1] + ) generates the nucleophilic imine CcNH (1). Reaction of 1 with acid chlorides R–COCl (R = Ph, Fc, and Cc+) yields the reference amide [Ph-CO-NH-Cc]+ (2 + ) and the amide-linked hetero- and homobimetallocenes [Fc-CO-NH-Cc]+ (3 + ) and [Cc-CO-NH-Cc]2+ (4 2+ ), respectively. Cation–anion interactions of charged amides 2 + –4 2+ in the solid state and in solution are probed by single crystal X-ray diffraction and NMR and IR spectroscopy. Intramolecular metal–metal interactions in donor–acceptor heterobimetallocene 3 + and in mixed-valent homobimetallocene 4 + (prepared electrochemically) are discussed within the Marcus–Hush framework aided by spectroelectrochemical experiments and time-dependent density functional theory calculations.

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The dicobaltocenium ion [Cc 2 NH] 2+ [H−1] 2+ was obtained via nucleophilic substitution of the nitro group of [Cc− NO 2 ] + by amino cobaltocenium [Cc−NH 2 ] + (Cc = Co(η 5 -C 5 H 4 )(η 5 -C 5 H 5 )). [H−1] 2+ is moderately acidic, giving the conjugate base 1 + after deprotonation (pK a = 16.36 in acetonitrile). Single-crystal X-ray diffraction analyses and quantum chemical calculations of the [H−1] 2+ /1 + acid/base pair show only minor geometric changes during the proton transfer. One-electron reduction of [H−1] 2+ at −1.32 V versus ferrocene furnishes [H−1] + , which is a strong hydrogen atom donor with a bond dissociation free energy (BDFE) of the NH group of only 44.6 kcal mol −1 . Hydrogen gas evolves from [H−1] + , generating cation 1 + . One-electron oxidation of 1 + at E p = +0.47 V gives the highly reactive aminyl radical 1 2+ . The BDFE of the NH group of [H−1] 2+ amounts to 85.9 kcal mol −1 . Spin trapping experiments confirm that 1 2+ abstracts a hydrogen atom from the CH 3 CN solvent, regenerating [H−1] 2+ . Consequently, the [H−1] 2+/+ redox couple is competent in the hydrogen evolution reaction and the [H−1] 2+ /1 2+ pair enables hydrogen atom abstraction from CH 3 CN. The [H−1] 2+ /[H−1] + /1 2+ ions exhibit a unique proton, electron, and hydrogen atom transfer reactivity.