Dinuclear Complexes of Flexidentate Pyridine-Substituted Formazanate Ligands

Abstract

In this work we show the utility of flexidentate pyridyl‐substituted formazanate ligands in assembling dinuclear coordinationcomplexes with iridium(III) and/or platinum(II) building blocks. The versatile binding modes of these ligands allow the preparation of several different dinuclear structures, highlighting the potential of these formazanates to serve as redoxactive supporting ligands for multimetallic complexes. The dinuclear complexes are typically prepared in a stepwise strategy, adding one metal unit at a time, with the coordination mode of the formazanate with the first metal dictating the binding mode in the final dinuclear structure. Eight of the new complexes, including both mononuclear precursors and dinuclear products, are structurally characterized by single‐crystal X‐ray diffraction, which along with NMR spectroscopy unambiguously establish ligand binding modes and symmetries of the compounds. All complexes are characterized by UVVis absorption spectroscopy and cyclic voltammetry. The frontier orbitals are localized on the formazanate ligand, and a characteristic, intense formazanate‐centered π→π* absorption band is observed in the absorption spectrum. Structureproperty relationships are established, relating the ligand binding mode to the redox properties and spectroscopic features. .<br>