title: Experimental and Theoretical Investigations of the Existence of Cu(II), Cu(III), and Cu(IV) in Copper Corrolato Complexes.
abstract: 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.
authors.affiliation: School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, 751005 (India).
authors.forename: Woormileela
authors.initials: W
authors.lastname: Sinha
authors.affiliation: Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstrasse 34-36, 14195 Berlin (Germany).
authors.forename: Michael G
authors.initials: MG
authors.lastname: Sommer
authors.affiliation: Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstrasse 34-36, 14195 Berlin (Germany).|Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany).
authors.forename: Naina
authors.initials: N
authors.lastname: Deibel
authors.affiliation: Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany).
authors.forename: Fabian
authors.initials: F
authors.lastname: Ehret
authors.affiliation: Universität Paderborn, Naturwissenschaftliche Fakultät, Department Chemie, Warburger Strasse 100, 33098 Paderborn (Germany).
authors.forename: Matthias
authors.initials: M
authors.lastname: Bauer
authors.affiliation: Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstrasse 34-36, 14195 Berlin (Germany). biprajit.sarkar@fu-berlin.de.
authors.forename: Biprajit
authors.initials: B
authors.lastname: Sarkar
authors.affiliation: School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, 751005 (India). sanjib@niser.ac.in.
authors.forename: Sanjib
authors.initials: S
authors.lastname: Kar
keywords: EPR spectroscopy; XANES measurements; copper corroles; higher oxidation states; spectroelectrochemistry