作者:Vesela Ugrinova、Bruce C. Noll、Seth N. Brown
DOI:10.1021/ic061201s
日期:2006.12.1
metalated readily by titanium(IV) isopropoxide, but the nature of the complexes formed depends on the linker structure. The biphenyl-bridged ligand gives only traces of a mononuclear complex, which is thermodynamically unstable with respect to oligomerization. The tolan-bridged ligand does form mononuclear complexes, but only as a mixture of geometric isomers. In contrast, the substituted 2,2'-bis-(2,4-dioxobutyl)biphenyl
制备了由2,2'-联苯二基,2,2'-托兰二基和2,2'-双(亚甲基)联苯部分连接的新型双(β-二酮)。所有这些都容易被异丙醇钛(IV)金属化,但是形成的配合物的性质取决于接头结构。联苯桥联的配体仅给出痕量的单核配合物,该配合物在低聚方面是热力学不稳定的。甲苯戊桥连的配体确实形成单核络合物,但仅作为几何异构体的混合物。相反,取代的2,2'-双-(2,4-二氧杂丁基)联苯配体R2BobH2(R = tBu,p-Tol)与Ti(OiPr)4反应,首先得到单体和低聚物,在过量的Ti(OiPr)4存在下加热可定量转化为单体。只能观察到通过(tBu2Bob)Ti(O-2,6-iPr2C6H3)2的晶体学确定为(R)-/(S)-非对映异构体的联苯和双(螯合)钛部分的相对结构。 。(R2Bob)Ti骨架的动力学和热力学鲁棒性通过与路易斯酸的反应得到证实。例如,(Tol2Bob)Ti(OiPr)2与三氟甲