We report the application of an iron(II) complex bearing a tetradentate donor substituted N-heterocyclic carbene ligand (NCCN, bis(pyridylimidazol-2-ylidene)methane) as an efficient catalyst for alkene epoxidation as well as alkane and arene oxidation reactions. By substitution of acetonitrile ligands a variety of isocyanide bearing complexes has been synthesized. Depending on the relative amount of isocyanide used for the reaction either mono(isocyanide)-substituted or tri(isocyanide)-substituted Fe(II) complexes were obtained. Dissociation of one of the pyridyl moieties in the latter case induces a meridional, tridentate NCC coordination, which was identified by single crystal X-ray crystallography. In course of the formation of the tri-substituted derivative a cis di(CN<i><sup>t</sup></i>Bu)-substituted Fe(II) complex was observed by NMR spectroscopy. The impact of the isocyanide ligands on the electronic structure of the iron complexes was investigated by cyclic voltammetry. Furthermore, immobilization of the iron(II) NCCN complex was achieved by analogous substitution of an axial acetonitrile ligand with an isocyanide functionalized polystyrene support. Implications of the substitutions on the catalytic behavior of the complexes were investigated.

Substitution of labile solvent ligands of an iron(II) NHC complex by isocyanides

251st National Meeting (2016)

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