Synthesis and characterization of M(ii) (M = Mn, Fe and Co) azafulvene complexes and their X3− derivatives

Abstract

The syntheses of M(II) (M = Mn, Fe, Co) complexes bearing the tris(5-cycloaminoazafulvene-2-methyl)amine (H₃N(afa^Cy)₃) ligand in its datively coordinated, tautomeric form is reported. The metal–azafulvene complexes [N(afa^Cy)₃M](OTf)₂ are generated in high yields, featuring a secondary coordination sphere composed of amino moieties from the ligand platform. To investigate the ability of the hydrogen bonding network to support hydrogen-bond accepting, coordinating anions, pseudohalide derivatives, [N(afa^Cy)₃MX](OTf) (X = NCS⁻, NCO⁻, N₃⁻) were synthesized by exposure of [N(afa^Cy)₃M](OTf)₂ to an equivalent of the corresponding salt, [(ⁿBu)₄N](X). Structural characterization of the products reveals two isomorphs of the desired species. One complex features a single hydrogen bonding interaction with the pseudohalide, while the second compound has two H-bonds from the secondary coordination sphere to the coordinated anion. These complexes showcase the structural and electron flexibility of the ligand platform, presenting a scaffold capable of accessing a different number of hydrogen bonds for stabilizing a given moiety.