Three-Coordinate Iron(II) Dialkenyl Compound with NHC Ligation: Synthesis, Structure, and Reactivity

The reaction of [(IPr2Me2)2FePh2] with PhCCPh furnished a three-coordinate iron­(II) dialkenyl complex, [(IPr2Me2)­Fe­(σ-CPhCPh2)2] (1, IPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene), that represents a rare example of isolable low-coordinate iron alkenyl complexes with a high-spin ground state. Complex 1 was characterized by 1H NMR spectroscopy, solution magnetic susceptibility measurement, Mössbauer spectroscopy, single-crystal X-ray diffraction study, and elemental analyses. A reactivity study revealed the reactions of 1 with PhCH2Cl to produce cross-coupling product Ph2CCPhCH2Ph (2), with [Cp2Fe]­[BArF4] to yield Ph2CCPh–CPhCPh2 (3), and with CO, 2,6-dimethylphenyl isocyanide, and phenyl azide to produce novel iron(0) and iron­(II) complexes 4–6 bearing triphenylvinyl-derived ligands. These transformations demonstrated the high reactivity of the low-coordinate iron alkenyl complex.