Syntheses, Structures and Reactivity of Terminal Phosphido Complexes of Iron(II) Supported by a β-Diketiminato Ligand

Abstract

We report the synthesis of the first series of terminal phosphido iron complexes supported by a β-diketiminato ligand (Dippnacnac) and their catalytic activity in dehydrocoupling of secondary phosphines. Anionic and neutral mono- or diphosphido complexes were obtained from the reaction of [(Dippnacnac)FeCl2Li(dme)2] with the R2PLi (R = iPr, tBu, Cy, Ph) phosphides by tuning the stoichiometric ratio, polarity of the solvent, and the bulkiness of the substituents at the P-atom. The structures of the synthesized compounds were determined by single-crystal X-ray diffraction, which revealed that the iron sites of the anionic complexes are four-coordinate, whereas those of the neutral complexes are three-coordinate with almost planar geometry. These phosphido iron complexes were also characterized by 1H NMR and zero-field Mössbauer spectroscopy. The thermal stability and reactivity of selected complexes were studied. The catalytic properties of the phosphido complexes were confirmed by investigating the conversion of diphenylphosphine to symmetrical 1,1,2,2-teraphenyldiphosphane.