Synthesis And Reactivity Of Silyl Iron,Cobalt And Nickel Complexes Bearing A [PSiP]-Pincer Ligand Via Si-H Bond Activation

Inert bond activation can be used for the study of the catalytic mechanism, it is committed to achieve the desired chemical transformation more directly by using cheap and easy to get raw materials in mild conditions, and it is an important direction of the future development in the chemical industry because of green chemistry and atom economy. In recent years, with the rise of silicone chemistry, the activation of the Si-H bonds to build different silicone molecules has begun to attract people’s attention. However, the Si-H bonds oxidative addition products compounds by reaction with small molecules directly are usually instable, which is not conducive to explore its properties and reactions, and largely restricted in Industrial applications. Thus significant interest has been attracted in building stable silyl metal complexes bearing pincer ligands.Pincer ligands are a well-known class of tridentate ancillary ligands that feature a central anionic donor atom flanked by two neutral donor groups. This inhibits the dissociation between metal and ligand as well as the process of ligand exchange. This structure not only improves the thermal stability and the chemical stability of its metal complexes to water and oxygen. Numerous examples of transition metal complexes supported by such ligands have been reported, and these complexes have demonstrated remarkable stoichiometric and reactivity properties in inert bond activation and TM catalysis.The main content of this paper is to design and synthesize of a new type of pincer silyl metal complexes via Si-H bond activation and explore their reactivity. Reactions of cheap eco-friendly low valence and electron-rich iron, cobalt and nickel complexes and PSiP pincer ligand had been systematic investigated. Not only silyl metal hydride complexes (Co(Ⅱ)-H, Co(Ⅲ)-H and Fe(Ⅱ)-H) but also the frozen intermediates η2-(Si-H)Ni(0) complexes were synthesized and characterized, which will have great theoretical significance. Furthermore, several corresponding halogenated Ni and Co complexes could be obtained directly from the reactions of simple inorganic salts NiCl2or CoCl2with PSiP ligand1in the presence of trimethylphosphine via Si-H bonds activation. In addition, the reactivity and catalytic activity of those complexes were also investigated.Those complexes were fully characterized and analyzed by31P、1H and13C NMR, IR spectroscopy, Melting point and elemental analysis, complex2and6also characterized by29Si NMR and discussed by DFT. Structures of some compounds have been confirmed by X-ray diffraction techniques.