The dinuclear dialkoxo-bridged complexes [(TiCl)2(μ-O2L)(μ-(η5-C5Me4SiMeO)2(μ-O)})] (O2L = 1,2-O2C2H41a, 1,2-O2C6H41b, 1,2-(OCH2)2C6H41c, O2SiPh21d) were obtained by reaction of [(TiCl2)2(μ-(η5-C5Me4SiMeO)2(μ-O)})] (A) with the corresponding dilithium salt (1a) or diol (1b, 1c, 1d). Alkylation of 1a and 1b with ClRMg afforded [(TiR)2(μ-O2L)(μ-(η5-C5Me4SiMeO)2(μ-O)})] (O2L = 1,2-O2C2H4, R = Me 2a, Bz 3a; O2L = 1,2-O2C6H4, R = Me 2b, Bz 3b). Addition of four equiv. of LiOiPr to A afforded [Ti(OiPr)2}2(μ-(η5-C5Me4SiMeO)2(μ-O)})] (4). Reaction of 1a with Al(C6F5)3 produced the elimination of the dialkoxo ligand to give [TiCl(C6F5)}2(μ-(η5-C5Me4SiMeO)2(μ-O)})] (5), whereas the same reaction of 1b with Al(C6F5)3 produced the oxo-alane adduct [(TiCl)2(μ-O2L)(μ-(η5-C5Me4SiMeO)2(μ-O·AlC6F5}3)})] (O2L = 1,2-O2C6H46) which was further transformed to give a mixture of 5 and [(TiCl)Ti(C6F5)}(μ-O2L)(μ-(η5-C5Me4SiMeO)2(μ-O)})] (O2L = 1,2-O2C6H47). One benzyl group of complexes 3 was abstracted with E(C6F5)3 (E = B, Al) to give the monoionic compounds [Ti(TiBz)(μ-O2L)(μ-(η5-C5Me4SiMeO)2(μ-O)})][BzE(C6F5)3] (O2L = 1,2-O2C2H4, E = B 8B, Al 8Al; O2L = 1,2-O2C6H4, E = B 9B), although 8Al was unstable in CD2Cl2 evolving to a mixture of compounds where [(TiBz)2(μ-Cl)(μ-(η5-C5Me4SiMeO)2(μ-O)})][BzAl(C6F5)3] (10) was identified, and compound 9B was also unstable at ambient temperature. Polymerization of ε-caprolactone was only achieved with the tetraalkoxo compound 4. All of these complexes were characterized by NMR spectroscopy and 1a, 1b and 7 by X-ray diffraction studies.
双核二酮桥配合物[(TiCl)2(μ-O2L)(μ-(η5-C5Me4SiMeO)2(μ-O)})](O2L = 1,2-O2C2H41a,1,2-O2C6H41b,1,2-(OCH2)2C6H41c、O2SiPh21d)是通过[(TiCl2)2(μ-(η5-C5Me4SiMeO)2(μ-O)}](A)与相应的二
锂盐(1a)或二元醇(1b、1c、1d)反应得到的。)用 ClRMg 烷基化 1a 和 1b,得到[(TiR)2(μ-O2L)(μ-(η5-C5Me4SiMeO)2(μ-O)})](O2L = 1,2-O2C2H4,R = Me 2a,Bz 3a;O2L = 1,2-O2C6H4,R = Me 2b,Bz 3b)。在 A 中加入四当量的 LiOiPr,得到 [Ti(OiPr)2}2(μ-(η5-C5Me4SiMeO)2(μ-O)})] (4)。1a 与 Al(
C6F5)3 反应后,二酮氧
配体被消除,得到 [TiCl( )}2(μ-(η5-C5Me4SiMeO)2(μ-O)})] (5)、而 1b 与 Al( )3 的相同反应生成了氧代
丙烷加合物[(TiCl)2(μ-O2L)(μ-(η5-C5Me4SiMeO)2(μ-O-Al }3)})](O2L = 1、2-O2C6H46)的混合物,进一步转化得到 5 和[(TiCl)Ti( )}(μ-O2L)(μ-(η5-C5Me4SiMeO)2(μ-O)})](O2L = 1,2-O2C6H47)的混合物。配合物 3 的一个苄基被 E( )3 (E = B、Al)抽取,得到单离子化合物 [Ti(TiBz)(μ-O2L)(μ-(η5-C5Me4SiMeO)2(μ-O)})][BzE( )3] (O2L = 1,2-O2C2H4,E = B 8B,Al 8Al;O2L=1,2-O2C6H4,E=B 9B),但 8Al 在 CD2Cl2 中不稳定,会演化成一种化合物混合物,其中 [(TiBz)2(μ-Cl)(μ-(η5-C5Me4SiMeO)2(μ-O)})][BzAl( )3](10)已经确定,化合物 9B 在环境温度下也不稳定。只有四烷氧基化合物 4 实现了
ε-己内酯的聚合。所有这些复合物都通过核磁共振光谱进行了表征,1a、1b 和 7 则通过 X 射线衍射研究进行了表征。