The Syntheses And Olefin Polymerization Of Catalysts With Arylsulfide Or Aryphosphide Ligands

The field of olefin polymerization catalysis has experienced Ziegler-Natta catalysts, metallocene catalysts and post-metallocene catalysts periods. Ziegler-Natta catalysts showed poor stereo selectivity for a-olefin polymerization. The high oxophilicity of early transition metal catalysts causes the active centre of metallocene catalyst to be poisoned by most functionalized olefins which contain O, S or N heteroatoms. A large amount of MAO or expensive fluorinated borate is generally required as cocatalyst for obtaining high activity. There is a great need to develop new catalyst systems which can provide high activity, high stereoselectivity, with no need of large amounts of expensive cocatalyst and good functional-group tolerance ability. For investigations of ethylene polymerization, the group IV metal complexes with the chelate atom O, N attracted more attention. Recently, scientists follow awfully with interest catalysts containing phenoxy-amide ligands bearing soft pendant donors because of their more highly active ethylene polymerization catalysts than the counterparts containing hard donors. In this dissertation, a series of half-zirconocene complexes with arylsulfide ligands, titanium complexes containing [O-N-S] ligands; nickel and palladium complexes with [C", N, S] or [C-, N, P] ligands were synthesized and characterized. The effects of catalyst structures, molar ratio of catalyst/cocatalyst, reaction temperature on polymerization reaction have been discussed in detail. The full dissertation was summarized as follows:1. A series of half-sandwich Group Ⅳ metal complexes with tridentate monoanionic phenoxy-imine arylsulfide [O-NS] and dianionic phenoxy-amine arylsulfide [O-N-S] ligands have been synthesized and characterized. Upon activation with methylaluminoxane (MAO), the catalytic behaviors of these complexes toward ethylene polymerization were investigated. Cp analogue complexes CpZr[O-N-S]Cl exhibited high activities up to1.58×107g PE-mol Zr-1·h-1, and CpZr[O-NS]Cl2up to8.2×106g PE·mol Zr-1·-h-1. Whereas Cp*complexes Cp*Zr[O-N-S]Cl, Cp analogue complexes CpTi[O-NS]Cl2and CpTi[O-N-S]Cl showed moderate activity for ethylene polymerization, dichloride complexes CpTi[O-NS]Cl2and CpZr[O-NS]Cb showed the higher catalytic activity and the products have fower molecular weight (My) than monochloride complexes CpTi[O-NS]Cl and CpZr[O-N-S]CL Remarkably, half-zirconocene complexes pre-catalyst exhibited excellent thermal stability at80℃.2. A new type of tridentate [O, N, S] Jigands were easily prepared in one step based on corresponding phenoxy-imine arylsulfide ligands. When deprotonated by nBuLi, such ligands can be used as tridentate dianionic ligands to synthesize dichlorotitanium, dichlorozirconium and dichlorohafnium complexes. Upon activation with methylaluminoxane (MAO), the catalytic behaviors of these complexes toward ethylene polymerization were investigated. The large steric hindrance at the ortho-position of S can weaken the bond of Ti-S to make the activity decreased, but the substituent of ortho-position of O made different influence. And the activity of titanium complex is higerthan zirconium and hafnium complexes.3. A series of tridentate monoanionic [C, N, X](X=S, P) nickel (Ⅱ)[(C6H4CH=NPh-2-XPh)NiBr](X=S, PPh) and palladium (Ⅱ) complexes [(C6H4CH=NPh-2-XPh)PdCI](X=S, PPh) were synthesized and characterized. With methylaluminoxane (MAO) as cocatalyst, these title complexes were not able to catalyze ethylene polymerization, but norbornene polymerization to afford vinyl addition type polynorbornene (PNB) with good catalytic activities up to8.78×106g of PNB (mol of Pd)-1h-1. The molecular weights of the polymers obtained by palladium (Ⅱ) complexes could not be determined because oftheir insolubility.