Copper(I) Chelation by Tetradentate NSSN Donor Ligands: Reversible Oxidation but no Oxygenation

Authors

  • Johannes Schnödt,

    1. Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart, Germany
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  • Monika Sieger,

    1. Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart, Germany
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  • Biprajit Sarkar,

    1. Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart, Germany
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  • Jan Fiedler,

    1. J. Heyrovský Institute of Physical Chemistry, v.v.i., Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague, Czech Republic
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  • Jorge S. Manzur,

    1. Departamento de Ciencias de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Tupper 2069, Santiago de Chile, CEDENNA, Chile
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  • Cheng-Yong Su,

    1. MOE Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, 510275, China
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  • Prof. Dr. Wolfgang Kaim

    Corresponding author
    1. Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart, Germany
    • Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart, Germany
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  • In Memory of Professor Hans-Georg von Schnering

Abstract

The copper(I) complexes [Cu(L4)](ClO4), L4 = 1,6-bis(N-methyl-1H-benzimidazol-2-yl)-2,5-dithiahexane (bmbdh) or 1,7-bis(N-methyl-1H-benzimidazol-2-yl)-2,6-dithiaheptane (bmdhp) were obtained and investigated through structure analysis (bmdhp compounds), cyclic voltammetry, UV/Vis/NIR and EPR spectroelectrochemistry. Structure comparison of the complexes [Cu(bmdhp)](ClO4) (1) and [Cu(bmdhp)](SO3CF3) (2) with the previously reported [CuI(bdhp)(H2O)](PF6)0.66(BF4)0.34 (4), bdhp = 1,7-bis(1H-benzimidazol-2-yl)-2,6-dithiaheptane, with the related [CuI(mmb)2](BF4) (5), mmb = 1-methyl-2-methylthiomethyl-1H-benzimidazole, with the oxidised [CuII(bmdhp)(H2O)](ClO4)2 (7), and with the zinc(II) species [Zn(bmbdh)(H2O)(SO3CF3)](SO3CF3) (8) and {[Zn(μ-bmdhp)(H2O)(SO3CF3)]2}(SO3CF3) (9) reveal a variety of coordination numbers, L4 ligand coordination modes, M–N bond lengths and especially N–M–N angles, affecting the accessibility of the central metal ions. Electronic consequences as evident from oxidation potentials and from EPR and absorption spectra of the copper(II) forms are discussed. The lack of reactivity of the copper(I) compounds towards O2 is attributed to steric shielding and to electronic effects from two π accepting thioether donors.

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