A Chiral Macrocyclic Tetra-N-Heterocyclic Carbene Yields an "All Carbene" Iron Alkylidene Complex.

ABSTRACT: The first chiral macrocyclic tetra-N-heterocyclic carbene (NHC) ligand has been synthesized. The macrocycle, prepared in high yield and large scale, was ligated onto palladium and iron to give divalent C₂ -symmetric square planar complexes. Multinuclear NMR and single crystal X-ray diffraction demonstrated that there are two distinct NHCs on each ligand, due to the bridging chiral cyclohexane. Oxidation of the iron(II) complex with trimethylamine N-oxide yielded a bridging oxo complex. Diazodiphenylmethane reacted with the iron(II) complex at room temperature to give a paramagnetic diazoalkane complex; the same reaction yielded the "all carbene" complex at elevated temperature. Electrochemical measurements support the assignment of the "all carbene" complex being an alkylidene.

SUBMITTER: DeJesus JF 

PROVIDER: S-EPMC7024548 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature