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

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, [((n)Bu)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.