Lehtonen Ari
Intelligent Materials Chemistry Research Group, Department of Chemistry, University of Turku, FI-20014 Turku, Finland.
Molecules. 2024 Feb 29;29(5):1088. doi: 10.3390/molecules29051088.
Redox non-innocent ligands react with metal precursors to form complexes where the oxidation states of the ligand and thus the metal atom cannot be easily defined. A well-known example of such ligands is bis(-aminophenol) ,'-bis(3,5-di-butyl-2-hydroxy-phenyl)-1,2-phenylenediamine, previously developed by the Wieghardt group, which has a potentially tetradentate coordination mode and four distinct protonation states, whereas its electrochemical behavior allows for five distinct oxidation states. This rich redox chemistry, as well as the ability to coordinate to various transition metals, has been utilized in the syntheses of metal complexes with ML, ML and ML stoichiometries, sometimes supported with other ligands. Different oxidation states of the ligand can adopt different coordination modes. For example, in the fully oxidized form, two N donors are sp-hybridized, which makes the ligand planar, whereas in the fully reduced form, the sp-hybridized N donors allow the formation of more flexible chelate structures. In general, the metal can be reduced during complexation, but redox processes of the isolated complexes typically occur on the ligand. Combination of this non-innocent ligand with redox-active transition metals may lead to complexes with interesting magnetic, electrochemical, photonic and catalytic properties.
氧化还原非惰性配体与金属前体反应形成配合物，其中配体的氧化态以及金属原子的氧化态难以轻易确定。这类配体的一个著名例子是双（-氨基苯酚），'-双（3,5-二丁基-2-羟基苯基）-1,2-苯二胺，此前由维格哈特小组开发，它具有潜在的四齿配位模式和四种不同的质子化状态，而其电化学行为允许有五种不同的氧化态。这种丰富的氧化还原化学性质以及与各种过渡金属配位的能力，已被用于合成具有ML、ML和ML化学计量比的金属配合物，有时还会有其他配体的支持。配体的不同氧化态可以采用不同的配位模式。例如，在完全氧化形式中，两个N供体是sp杂化的，这使配体呈平面状，而在完全还原形式中，sp杂化的N供体允许形成更灵活的螯合结构。一般来说，金属在络合过程中可以被还原，但分离出的配合物的氧化还原过程通常发生在配体上。这种非惰性配体与氧化还原活性过渡金属的结合可能会导致具有有趣的磁性、电化学、光子和催化性质的配合物。
