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Experimental and Theoretical Investigations of the Existence of Cu II , Cu III , and Cu IV in Copper Corrolato Complexes
Author(s) -
Sinha Woormileela,
Sommer Michael G.,
Deibel Naina,
Ehret Fabian,
Bauer Matthias,
Sarkar Biprajit,
Kar Sanjib
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201507330
Subject(s) - copper , redox , chemistry , catalysis , electron paramagnetic resonance , xanes , electrochemistry , oxidation state , inorganic chemistry , metal , crystallography , spectroscopy , organic chemistry , nuclear magnetic resonance , physics , electrode , quantum mechanics
The most common oxidation states of copper in stable complexes are +I and +II. Cu III complexes are often considered as intermediates in biological and homogeneous catalysis. More recently, Cu IV species have been postulated as possible intermediates in oxidation catalysis. Despite the importance of these higher oxidation states of copper, spectroscopic data for these oxidation states remain scarce, with such information on Cu IV complexes being non‐existent. We herein present the synthesis and characterization of three copper corrolato complexes. A combination of electrochemistry, UV/Vis/NIR/EPR spectroelectrochemistry, XANES measurements, and DFT calculations points to existence of three distinct redox states in these molecules for which the oxidation states +II, +III, and +IV can be invoked for the copper centers. The present results thus represent the first spectroscopic and theoretical investigation of a Cu IV species, and describe a redox series where Cu II , Cu III , and Cu IV are discussed within the same molecular platform.