Volume 24, Issue 48 p. 12613-12622
Full Paper

Chromium Complexes with Oxido and Corrolato Ligands: Metal-Based Redox Processes versus Ligand Non-Innocence

Antara Garai

Antara Garai

School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, Khordha, 752050 India

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Sebastian Sobottka

Sebastian Sobottka

Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34–36, 14195 Berlin, Germany

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Rahel Schepper

Rahel Schepper

Universität Paderborn, Naturwissenschaftliche Fakultät, Department Chemie, Warburger Straße 100, 33098 Paderborn, Germany

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Woormileela Sinha

Woormileela Sinha

School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, Khordha, 752050 India

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Prof. Dr. Matthias Bauer

Corresponding Author

Prof. Dr. Matthias Bauer

Universität Paderborn, Naturwissenschaftliche Fakultät, Department Chemie, Warburger Straße 100, 33098 Paderborn, Germany

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Prof. Dr. Biprajit Sarkar

Corresponding Author

Prof. Dr. Biprajit Sarkar

Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34–36, 14195 Berlin, Germany

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Dr. Sanjib Kar

Corresponding Author

Dr. Sanjib Kar

School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, Khordha, 752050 India

Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400094 India

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First published: 08 June 2018
Citations: 17

Dedicated to Prof. Dietmar Stalke on the occasion of his 60th birthday

Graphical Abstract

Metal- or ligand-centered redox? UV/Vis/NIR/EPR spectroelectrochemical and XANES measurements, together with DFT calculations, have been applied to address the issue of chromium- versus corrolato-centered redox processes, and the accessibility (or not) of CrIV, CrV, and CrVI in these complexes, as well as their spin states.

Abstract

Metal- versus ligand-centered redox processes and the effects of substituents on the ligands on the spectroscopic properties of the metal complexes are at the heart of research on metal complexes with non-innocent ligands. This work presents three examples of chromium complexes that contain both oxido and corrolato ligands, with the substituents on the corrolato ligands being different in the three cases. Combined X-ray crystallographic, electrochemical, UV/Vis/NIR/EPR spectroelectrochemical, and EXAFS/XANES measurements, together with DFT calculations, have been used to probe the complexes in three different redox forms. This combined approach makes it possible to address questions related to chromium- versus corrolato-centered redox processes, and the accessibility (or not) of CrIV, CrV, and CrVI in these complexes, as well as their spin states. To the best of our knowledge, these are the first EXAFS/XANES investigations on Cr-corrolato complexes in different redox forms, and hence these data should set benchmarks for future investigations on such complexes by this method.

Conflict of interest

The authors declare no conflict of interest.