Synthesis and Characterization of Multimetallic Clusters Featuring Iron, Cobalt, and 2,6-bis(trialkylsilylamino)pyridines

Extended metal atom chain (EMAC) complexes are multimetallic complexes of three or more metals, often containing M-M bonds, with the metal ions arranged linearly. These complexes have significant potential as molecular wires. They can elicit unique physical properties and reactivities, sometimes a result of direct magnetic exchange between metal centers, especially when incorporating first row transition metals. The synthesis of the first linear, triiron (II) complex with 2,6-bis[(trimethylsilyl)amino]pyridine (H2LMe) featuring Fe-Fe bonding from our group, Fe3LMe3, motivated the expansion of linear multimetallic EMAC complexes with Fe and Co, incorporating M-M bonds. The complexes investigated herein were supported by an expanded ligand library of H2LR, for example 2,6-bis[(triethylsilyl)amino]pyridine (H2LEt), and 2,6-bis[(dimethylisopropylsilyl)amino]pyridine (H2LiPr), to probe and compare physical properties and reactivity to Fe3LMe3, including effects of ligand sterics, ligand donor ability, metal identity, magnetism, and redox. Reported herein is the first worthy congener for Fe3LMe3, a linear tricobaltous complex, Co3LMe3, to compare magnetic behaviors, and electrochemical and physical properties when switching metals. The complexes are isostructural, however investigations of the tricobaltous complex revealed many differences when compared to the first linear triferrous complex. A synthesis approach with Fe2Mes4 to modify and improve the synthesis of Fe3L3Me was also reported. The compounds investigated were characterized by 1H NMR, 13C NMR, Evans method, UV-Vis spectroscopy, X-ray diffraction, cyclic voltammetry, and computational analysis