Synthesis and characterization of stable tripodal silyl iron and nickel complexes

•Tripodal silyl iron and nickel complexes.•Iron hydrido complex.•Nickel hydrido complex.•Tripodal silyl ligand.

The synthesis and reactivity of a series of iron and nickel complexes supported by tris(phosphino)silyl ligand (o-(Ph2P)C6H4)3SiH (1) have been explored. Iron hydrido complex (o-(Ph2P)C6H4)3SiFeH(PMe3) (2) was generated by combination of 1 with Fe(PMe3)4. 1 reacted with FeMe2(PMe3)4 delivered five-coordinate paramagnetic Fe(II) species (o-(Ph2P)C6H4)3SiFeMe (3). 1 reacted with Ni(PMe3)4 in THF at room temperature afforded Ni(0) complex (o-(Ph2P)C6H4)(o-(Ph2P)C6H4)2(η2-(Si-H))Ni(PMe3) (4), whereas the oxidative addition product (o-(Ph2P)C6H4)3SiNiH (5) was obtained by heating Ni(PMe3)4 and 1 in toluene at 80 °C for 20 h. The nickel halide complexes (o-(Ph2P)C6H4)3SiNiX (X = Cl (6), Br (7), I (8)) were synthesized by combination of Cl2MeSiH, EtBr, or CH3I with 4. Reaction of 1 with NiMe2(PMe3)3 produced Ni(II) complex (o-(Ph2P)C6H4)3SiNiMe (9). The molecular structures of complexes 2, 5 and 6 were determined by X-ray single crystal diffraction.

Graphical abstractThe synthesis and reactivity of a series of tripodal silyl iron and nickel complexes supported by tris(phosphino)silyl ligand 1 are reported via the activation of Si–H bonds. These complexes are very stable in air. The catalytic activity study showed that the hydrido iron complex, (o-(Ph2P)C6H4)3SiFeH(PMe3) (2), has no effect on the reduction of carbonyl compounds. The inertness might be attributed to the “crowded benzene rings” of complex 2.Figure optionsDownload full-size imageDownload as PowerPoint slide