Synthesis, Characterization, and Alkyne Trimerization Catalysis of a Heteroleptic Two-Coordinate FeI Complex

The synthesis of the first heteroleptic, two-coordinate FeI complex IPr–Fe–N­(SiMe3)­DIPP (1) (IPr = 1,3-bis­(2,6-diisopropylphenyl)­imidazol-2-ylidene; DIPP = 2,6-iPr2–C6H3) is reported. Protonation of the FeII bis­(amido) complex Fe­[N­(SiMe3)­DIPP]2 followed by addition of IPr and reduction by potassium graphite in a one-pot reaction results in good yields of 1. The redox activity of 1 and comparison between 1 and its reduction product by 57Fe Mössbauer spectroscopy are discussed, and the reduction was found to be metal-based rather than ligand-based. The activity of 1 toward the catalytic cyclotrimerization of terminal and internal alkynes is described.