1. Application Of Electron-rich Iron, Cobalt And Nickel Complexes Supported By Phosphine Ligands In C-H Bond Activation 2.Synthesis And Properties Of High-valent Transition-metal Phosphinio-methyliden/Yne Complexes

Carbon-hydrogen bond activation is of great importance not only in the research on fundamental theories but also in industrial applications. Many of these studies have involved C-H bond activation mediated by transitionemetal complexes. Pd, Ru, Rh based catalysts have attracted much more attention in C-H activation and catalysis. Fe, Co and Ni complexes are relatively underdeveloped, although they have potentially lower cost and environmental impact. Trimethylphosphine is a kind of good ligand with the advantages of strong ability of coordination, convenient preparation and simple spectrometry. Cobalt, Iron, Nickel complexes supported by trimethylphosphine are so activated that they can cut C-H bonds.Main contents of this dissertation are shown as below:1. The C-H bond activations in 1,1’-bis(diphenylphosphino)cobaltocene and 1,1’-bis(diphenylphosphino)ferrocene were investigated using Cobalt, Iron, Nickel complexes supported by trimethylphosphine. Unexpectedly, C-H activation with a P-donor group did not occur, instead a series of novel dinuclear complexes as products of ligand exchange were formed. This research can provide the novel methodology to prepare dinuclear half-sandwich complexes, it also has enriched the structural information of dinuclear half-sandwich complexes of transition-metal compounds.2. The C-H bond activations in dibenzylpenylphosphine were investigated using Cobalt, Iron complexes supported by trimethylphosphine. The products were fully characterized and the properties with small molecules were tested. Since the first transition metal complexes with a formal metal-carbon triple bond reported by E. O. Fischer et al. in 1973, carbyne or alkylidyne complexes have attracted considerable attention because of their interesting properties and significance as catalysts or reagents in the synthesis of organometallic and organic compounds. Until now hundreds of carbyne complexes are isolated and characterized, some of them are used as olefins, alkyne polymerization catalysts.Phosphonioalkylidyne complexes as a kind of special carbyne complexes(M=C—PR3(?)M=C=PR3) could be regarded as phosphorous ylide substituted by double-metal. Due to the special chemical properties, they might have potential application in organic synthesis and catalysis. Very few high-valent transition metal phosphonio methylidyne complexes with d0 electron configuration are known so far.1. Synthesis of high-valent transiton metal tantalum ylide adduct complexesThe chemistry of transition-metal phosphonium ylide complexes has attracted a lot attention because of their potential application in organic synthesis and catalytic fields. Ylide adduct complexes are important precursor for the formation of phosphonio methylidyne complexes of transition metal with d0 electron configurations. Herein we employed H2C=PPh3, H2C=P(nBu)3, H2C=PMe3 and studied their reactions with cyclopentadienyl (Cp) tantulum (V) tetrachloride and tetramethylcyclopendienyl tantulum (V) tetrachloride, finally three ylide adduct complexes CpTaCl4[H2C-P(nBu)3] (28), CpTaCl4[H2C-PMe3] (29), (C5Me4H)TaCl4[H2C-PPh3] (30) were isolated.2. Synthesis of high-valent transition metal tantulum phosphonio methylidyne complexesThe phosphonio(methylidyne) complex (C5Me4H)Ta(=C—PPh3)(=CHPPh3) (31) was obtained from transylidation reactions of tetramethylcyclopendienyl tantulum (V) tetrachloride with 5 equiv of Ph3P=CH2. The complex was fully characterized by 1H, 13C and 31P NMR. The structrure has been confirmed by X-ray diffraction techniques.3. Property of high-valent transition metal titanium phosphonio methylidene complex A simple synthesis of a-phosphonio(methylidene) complex of titanium [Cp*TiCl2(=CH-PPh3)] was reported by Wang et al. Herein NaN(SiMe3)2 was used to increase the yield and shorten the reaction time. Also the CO insert product [Cp*TiCl2(OCCH)PPh3] (33) was isolated and characterized after the reaction of [Cp*TiCl2(=CH-PPh3)] with CO.