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  Molecular and Electronic Structure of Four‐ and Five‐Coordinate Cobalt Complexes Containing Two o‐Phenylenediamine‐ or Two o‐Aminophenol‐Type Ligands at Various Oxidation Levels: An Experimental, Density Functional, and Correlated ab initio Study

Bill, E., Bothe, E., Chaudhuri, P., Chlopek, K., Herebian, D., Kokatam, S., et al. (2004). Molecular and Electronic Structure of Four‐ and Five‐Coordinate Cobalt Complexes Containing Two o‐Phenylenediamine‐ or Two o‐Aminophenol‐Type Ligands at Various Oxidation Levels: An Experimental, Density Functional, and Correlated ab initio Study. Chemistry – A European Journal, 11(1), 204-224. doi:10.1002/chem.200400850.

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 Creators:
Bill, Eckhard1, Author              
Bothe, Eberhard1, Author              
Chaudhuri, Phalguni1, Author              
Chlopek, Krzysztof1, Author              
Herebian, Diran1, Author              
Kokatam, Swarnalatha1, Author              
Ray, Kallol1, Author              
Weyhermüller, Thomas1, Author              
Neese, Frank1, Author              
Wieghardt, Karl1, Author              
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1Research Department Wieghardt, Max Planck Institute for Bioinorganic Chemistry, Max Planck Society, ou_3023881              

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Free keywords: ab initio calculations; cobalt; density functional calculations; nickel; radical ions
 Abstract: The bidentate ligands N‐phenyl‐o‐phenylenediamine, H2(2), or its analogue 2‐(2‐trifluoromethyl)anilino‐4,6‐di‐tert‐butylphenol, (4), react with [CoII(CH3CO2)2]⋅4H2O and triethylamine in acetonitrile in the presence of air yielding the square‐planar, four‐coordinate species [Co(2LN)2] (1) and [Co(4LO)2] (4) with an S=1/2 ground state. The corresponding nickel complexes [Ni(4LO)2] (8) and its cobaltocene reduced form [CoIII(Cp)2][Ni(4LO)2] (9) have also been synthesized. The five‐coordinate species [Co(2LN)2(tBu‐py)] (2) (S=1/2) and its one‐electron oxidized forms [Co(2LN)2(tBu‐py)](O2CCH3) (2 a) or [Co(2LN)2I] (3) with diamagnetic ground states (S=0) have been prepared, as has the species [Co(4LO)2(CH2CN)] (7). The one‐electron reduced form of 4, namely [Co(Cp)2][Co(4LO)2] (5) has been generated through the reduction of 4 with [Co(Cp)2]. Complexes 1, 2, 2 a, 3, 4, 5, 7, 8, and 9 have been characterized by X‐ray crystallography (100 K). The ligands are non‐innocent and may exist as catecholate‐like dianions (2)2−, (4)2− or π‐radical semiquinonate monoanions (2).−, (4).− or as neutral benzoquinones (2)0, (4)0; the spectroscopic oxidation states of the central metal ions vary accordingly. Electronic absorption, magnetic circular dichroism, and EPR spectroscopy, as well as variable temperature magnetic susceptibility measurements have been used to experimentally determine the electronic structures of these complexes. Density functional theoretical (DFT) and correlated ab initio calculation have been performed on the neutral and monoanionic species [Co(1LN)2]0,− in order to understand the structural and spectroscopic properties of complexes. It is shown that the corresponding nickel complexes 8 and 9 contain a low‐spin nickel(II) ion regardless of the oxidation level of the ligand, whereas for the corresponding cobalt complexes the situation is more complicated. Spectroscopic oxidation states describing a d6 (CoIII) or d7 (CoII) electron configuration cannot be unambiguously assigned.

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Language(s): eng - English
 Dates: 2004-08-172004-12-152004-12-17
 Publication Status: Published in print
 Pages: 21
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1002/chem.200400850
 Degree: -

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Title: Chemistry – A European Journal
  Other : Chem. – Eur. J.
  Other : Chem. Eur. J.
Source Genre: Journal
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Publ. Info: Weinheim : Wiley-VCH
Pages: - Volume / Issue: 11 (1) Sequence Number: - Start / End Page: 204 - 224 Identifier: ISSN: 0947-6539
CoNE: https://pure.mpg.de/cone/journals/resource/954926979058