Redox-Rich Metallocene Tetrazene Complexes: Synthesis, Structure, Electrochemistry, and Catalysis

Stefan Vanicek; Markus Jochriem; Christopher Hassenrück; Souvik Roy; Holger Kopacka; Klaus Wurst; Thomas Müller; Rainer F Winter; Erwin Reisner; Benno Bildstein

doi:10.1021/acs.organomet.8b00681

Redox-Rich Metallocene Tetrazene Complexes: Synthesis, Structure, Electrochemistry, and Catalysis

Organometallics. 2019 Mar 25;38(6):1361-1371. doi: 10.1021/acs.organomet.8b00681. Epub 2018 Nov 8.

Affiliations

¹ Institute of General, Inorganic and Theoretical Chemistry, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria.
² Department of Chemistry, University of Konstanz, Universitätsstrasse 10, D-78457 Konstanz, Germany.
³ Christian Doppler Laboratory for Sustainable SynGas Chemistry, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
⁴ Institute of Organic Chemistry, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria.

Abstract

Thermal or photochemical metal-centered cycloaddition reactions of azidocobaltocenium hexafluoridophosphate or azidoferrocene with (cyclooctadiene)(cyclopentadienyl)cobalt(I) afforded the first metallocenyl-substituted tetrazene cyclopentadienyl cobalt complexes together with azocobaltocenium or azoferrocene as side products. The trimetallic CpCo compounds are highly conjugated, colored, and redox-active metallo-aromatic compounds, as shown by their spectroscopic, structural, and electrochemical properties. The CpCo-tetrazenido complex with two terminally appended cobaltocene units catalyzes electrochemical proton reduction from acetic acid at a mild overpotential (0.35 V). Replacing cobaltocene with ferrocene moieties rendered the complex inactive toward catalysis.