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

The reaction of [(IPr2Me2)(2)FePh2] with PhC equivalent to CPh furnished a three-coordinate iron(II) dialkenyl complex, [(IPr2Me2)Fe(sigma-CPh=CPh2)(2)] (1, IPr2Me2 = 1,3-diisopropy1-4,5-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 H-1 NMR spectroscopy, solution magnetic susceptibility measurement, Mossbauer spectroscopy, single-crystal X-ray diffraction study, and elemental analyses. A reactivity study revealed the reactions of 1 with PhCh(2)C1 to produce cross-coupling product Ph2C=CPhCh(2)Ph (2), with [Cp2Fe]-[BAr4F] 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.