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    Redox Noninnocence in Coordinated 2-(Arylazo)pyridines: Steric Control of Ligand-Based Redox Processes in Cobalt Complexes

    Ghosh, Pradip and Samanta, Subhas and Roy, Suman K and Joy, Sucheta and Krämer, Tobias and McGrady, John E. and Goswami, Sreebrata (2013) Redox Noninnocence in Coordinated 2-(Arylazo)pyridines: Steric Control of Ligand-Based Redox Processes in Cobalt Complexes. Inorganic Chemistry, 52 (24). pp. 14040-14049. ISSN 0020-1669

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    A series of cobalt complexes of ligands based on the 2-(arylazo)pyridine architecture have been synthesized, and the precise structure and stoichiometry of the complexes depend critically on the identity of substituents in the 2, 4, and 6 positions of the phenyl ring. The 2-(arylazo)pyridine motif can support either CoII complexes with neutral ligands, CoIICl2(La )2 (1), CoIICl2(Lc )2 (3), [CoIICl(Lb )2]2(PF6)2 (5[PF6]2), or CoIII complexes of reduced 2-(arylazo)pyridine ligand radical anions, L•−, CoIIICl(Lb•−)2 (2), CoIIICl(Lc•−)2 (4), and CoIIIMe(Lb•−)2 (6). All three members of the latter class are based on approximately trigonal-bipyramidal CoX- (L•−)2 architectures [L = 2-(arylazo)pyridine] with two azo nitrogen atoms and the X ligand (X = Cl or Me) in the equatorial plane and two pyridine nitrogen atoms occupying axial positions. Density functional theory suggests that the electronic structure of the CoIII complexes is also dependent on the identity of X: the strong σ-donor methyl gives a low-spin (S = 0) configuration, while the σ/π-donor chloro gives an intermediate-spin (S = 1) local configuration. In certain cases, one-electron reduction of the CoIIX2L2 complex leads to the formation of CoIIIX(L•−)2; i.e., reduction of one ligand induces a further one-electron oxidation of the metal center with concomitant reduction of the second ligand.

    Item Type: Article
    Keywords: Redox Noninnocence; Coordinated 2‑(Arylazo)pyridines; Steric Control; Ligand-Based; Redox Processes; Cobalt Complexes;
    Academic Unit: Faculty of Science and Engineering > Chemistry
    Faculty of Science and Engineering > Research Institutes > Hamilton Institute
    Item ID: 15509
    Identification Number:
    Depositing User: Tobias Kraemer
    Date Deposited: 15 Feb 2022 15:20
    Journal or Publication Title: Inorganic Chemistry
    Publisher: American Chemical Society
    Refereed: Yes
    Use Licence: This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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