联苯基桥连双核茂锆化合物的合成及催化乙烯聚合

Synthesis and Application in Ethylene Polymerization of p-Biphenylene-bridged Dinuclear Zirconocenes

4,4′-二溴联苯与 n-Bu Li反应得到对 -联苯基二锂 ,再与四甲基环戊烯酮进行羰基加成 ,酸催化脱水 ,一步得到对 -联苯基桥连四甲基环戊二烯配体 4 -( C5Me4H) C6H4-C6H4( C5Me4H ) -4 ( 1 ) .配体 1相继与n-Bu Li和 Zr Cl4反应得到相应的联苯基桥连双 (单茂三氯化锆 ) 4 -( C5Me4Zr Cl3 ) C6H4— C6H4( C5Me4Zr Cl3 ) -4 ,不经分离直接与环戊二烯基锂或茚基锂反应得到相应的双核锆化合物 4 -( C5Me4Zr Cl2 Cp′) C6H4— C6H4·( C5Me4Zr Cl2 Cp′) -4 [Cp′=C5H5( 2 ) ,C9H7( 3) ].研究了在 MAO( Methyl Aluminoxane)助催化下 ,化合物 2和 3对乙烯聚合的催化性能 .化合物 2和 3都显示了非常高的催化活性 ,并在较高的温度下达到最高活性 .

?Dibromobiphenyl reacted with n-BuLi to form 4,4′-dilithiobiphenyl, which further reacted with 2,3,4,5-tetramethylcyclopent-2-enone following the elimination of water to give the ligand 4-(C 5Me 4H)C 6H 4-C 6H 4(C 5Me 4H)-4(1). Ligand 1 reacted with n-BuLi and ZrCl 4 to form the p-biphenylene-bridged dinuclear tetramethylcyclopentadienyl zirconium trichlorides 4-(C 5Me 4ZrCl 3)·C 6H 4-C 6H 4(C 5Me 4ZrCl 3)-4, which reacted in situ with cyclopentadienyl lithium(CpLi) or indenyl lithium(IndLi) to give the corresponding p-biphenylene-bridged dinuclear zirconocenes 4-(C 5Me 4ZrCl 2Cp′)C 6H 4-C 6H 4(C 5Me 4ZrCl 2Cp′)-4 [Cp′= Cp([STHZ]2), Ind(3)]. The zirconocenes 2 and 3. The zirconocenes 2 and 3 were characterized by 1H NMR, MS spectra and elemental analysis, and were studied for ethylene polymerization with methyl aluminoxane(MAO) as cocatalyst. Both 3 and 4 show very high activities and reach the maximum at a higher temperature, indicating that the introduction of the p-biphenylene-bridge increased the catalytic activity and thermal stability of the dinuclear zirconocene catalysts.