Coupling of an N‐Heterocyclic Carbene on Iron with Alkynes to Form η⁵‐Cyclopentadienyl‐Diimine Ligands

Abstract

A cyclometalated N‐heterocyclic carbene ligand in a half‐sandwich iron complex was found to couple with alkynes, leading to a unique type of ring opening of the carbene ligand and the formation of ferrocenyl–diimine complexes. An intermediary iron complex obtained from the reaction with phenylacetylene reveals that the ring opening follows the formation of a fused heterocycle consisting of an imidazole ring and two alkynes.