Synthetic routes leading to the first polyhedral oligosilsesquioxane derivatives incorporating niobium are reported. Tetrasilanol (c-C6H11)(6)Si6O7(OH)(4) (2), for which an improved laboratory-scale synthesis is reported, cleanly reacts with Nb(OEt)(5) to afford the dinuclear niobasilsesquioxane [(c-C6H11)(6)Si6O11-NbOEt](2) ( 3), which slowly converts to the tetranuclear mu-oxo species 4 in the presence of moisture. A structurally different mu-ethoxy-bridged dinuclear niobasilsesquioxane, [(c-C6H11)(7)Si7O12NbOEt(mu-OEt)](2) ( 6), is readily accessible from (c-C6H11)(7)Si7O9(OH)(3) (5) and Nb(OEt)(5). The molecular structures of 2, 3, 4, and 6 have been determined by X-ray diffraction.
The synthesis and catalytic activity of some new titanium(IV) complexes with incompletely condensed Cy6Si6O7(OH)4 and endo-Cy8Si8O11(OH)2 (Cy = c-C6H11) silsesquioxane cages have been carried out with the aim of investigating new Ti silsesquioxane frameworks as molecular models of titanium active sites of catalysts prepared by grafting Ti(IV) precursors on the surface or in a matrix of mesoporous silica
一些不完全缩合的Cy 6 Si 6 O 7(OH)4和内-Cy 8 Si 8 O 11(OH)2(Cy = cC 6 H 11)倍半硅氧烷笼的新型钛(IV)配合物的合成和催化活性为了研究新的倍半硅氧烷框架作为催化剂的钛活性位的分子模型而进行的研究是通过将Ti(IV)前体接枝到介孔二氧化硅的表面或基质中而制备的。倍半硅氧烷Cy 6 Si 6 O 7(OH)4,负有4个潜在反应性OH基团,当与TiCpCl反应3(CP =η 5 -C 5 H ^ 5),得到新的物种[赛扬6的Si 6 ö 12的Ti 2(CP)2 ],具有两个钛原子通过连接XANES和EXAFS光谱学研究证实,一个μ氧桥。通过内-Cy 8 Si 8 O 11(OH)2与[Ti(o -C 6 H 4 O 2)(OCH 2 CH 3)的反应如图2所示,如X射线衍射研究所示,获得了新的配合物[Cy 8 Si 8 O 11 O 2 ] 2
Base-catalyzed cleavage and homologation of polyhedral oligosilsesquioxanes
作者:Frank J. Feher、Raquel Terroba、Joseph W. Ziller
DOI:10.1039/a906397h
日期:——
Readily available Cy6Si6O9 2 (Cy = c-C6H11) reacts with aqueous NEt4OH in THF to afford endo-C2h-Cy6Si6O7(OH)4 3a, which upon further hydrolysis produces CySi(OH)3 fragments capable of reacting with 3a to produce endo-C3-Cy7Si7O9(OH)3 1b; the reaction of 2 with aqueous NEt4OH in the presence of (vinyl)Si(OMe)3 affords endo-Cs-Cy6(vinyl)Si7O9(OH)3 1c via trapping of 3a with monosilanes derived from (vinyl)Si(OMe)3.
作者:Volker Lorenz、Steffen Blaurock、Helmar Görls、Frank T. Edelmann
DOI:10.1021/om0606587
日期:2006.12.1
Synthetic routes leading to the first polyhedral oligosilsesquioxane derivatives incorporating niobium are reported. Tetrasilanol (c-C6H11)(6)Si6O7(OH)(4) (2), for which an improved laboratory-scale synthesis is reported, cleanly reacts with Nb(OEt)(5) to afford the dinuclear niobasilsesquioxane [(c-C6H11)(6)Si6O11-NbOEt](2) ( 3), which slowly converts to the tetranuclear mu-oxo species 4 in the presence of moisture. A structurally different mu-ethoxy-bridged dinuclear niobasilsesquioxane, [(c-C6H11)(7)Si7O12NbOEt(mu-OEt)](2) ( 6), is readily accessible from (c-C6H11)(7)Si7O9(OH)(3) (5) and Nb(OEt)(5). The molecular structures of 2, 3, 4, and 6 have been determined by X-ray diffraction.