Direct Synthesis of Iron(0) N‑Heterocyclic Carbene Complexes by Using Fe₃(CO)₁₂ and Their Application in Reduction of Carbonyl Groups

Iron Fe­(NHC)­(CO)₄ complexes were formed by direct reaction of Fe₃(CO)₁₂ with equimolecular amounts of NHC imidazolium halide precursors; addition of base was not needed in this reaction. When excess (9:1 ratio) 1,3-dimesitylimidazolium chloride is reacted with the iron cluster Fe₃(CO)₁₂, a mixture of Fe­(IMes)­(CO)₄ and Fe­(IMes)₂(CO)₃ is obtained. Single crystals of Fe­(IMes)­(CO)₄ and crystals resulting from the cocrystallization of Fe­(IMes)­(CO)₄ and Fe­(IMes)₂(CO)₃ have been studied by X-ray diffraction. These iron(0) complexes were found to catalyze the reduction of benzaldehydes

Direct Synthesis of Iron(0) N‑Heterocyclic Carbene Complexes by Using Fe₃(CO)₁₂ and Their Application in Reduction of Carbonyl Groups

Iron Fe­(NHC)­(CO)₄ complexes were formed by direct reaction of Fe₃(CO)₁₂ with equimolecular amounts of NHC imidazolium halide precursors; addition of base was not needed in this reaction. When excess (9:1 ratio) 1,3-dimesitylimidazolium chloride is reacted with the iron cluster Fe₃(CO)₁₂, a mixture of Fe­(IMes)­(CO)₄ and Fe­(IMes)₂(CO)₃ is obtained. Single crystals of Fe­(IMes)­(CO)₄ and crystals resulting from the cocrystallization of Fe­(IMes)­(CO)₄ and Fe­(IMes)₂(CO)₃ have been studied by X-ray diffraction. These iron(0) complexes were found to catalyze the reduction of benzaldehydes

Cyclopentadienyl–Silsesquioxane Titanium Complexes: Highly Active Catalysts for Epoxidation of Alkenes with Aqueous Hydrogen Peroxide

Titanium complexes bearing an unprecedented tridentate cyclopentadienyl–silsesquioxanate ligand provide a new class of efficient and selective catalysts for epoxidation of olefins with aqueous hydrogen peroxide under homogeneous conditions

Cationic Half-Sandwich Iron(II) and Iron(III) Complexes with N‑Heterocyclic Carbene Ligands

The cationic piano-stool iron complexes containing the N-heterocyclic carbene ligand tethered to a tetramethylcyclopentadienyl ring [(Cp*-NHC)­Fe­(CO)­(L)]­[X] (L = NCMe, DMSO; X = BF₄, OTf) have been prepared and analyzed by spectroscopic, electrochemical, and crystallographic methods. Oxidation reactions of the cationic complex [(Cp*-NHC)­Fe­(CO)­(NCMe)]­[BF₄] (<b>2</b>) with silver tetrafluoroborate and <i>tert</i>-butyl hydroperoxide in acetonitrile yield the dicationic iron­(III) complexes [(Cp*-NHC)­Fe­(NCMe)₂]­[BF₄]₂ and [(Cp*-NHC)­Fe­(H₂O)]­[BF₄]₂, respectively. When the reaction of <b>2</b> with AgBF₄ is performed in dichloromethane, the cationic complex [(Cp*-NHC)­FeCl]­[BF₄] is obtained. These new iron­(III) complexes have been characterized by Mössbauer spectroscopy and in one case by X-ray diffraction studies. DFT calculations were used to rationalize experimental results. The cationic complex [(Cp*-NHC)­Fe­(CO)­(NCMe)]­[OTf] is catalytically active toward the reduction of benzaldehyde and acetophenone using phenylsilane under neat conditions and in the absence of visible light irradiation