Kapoor Ramesh N, Cervantes-Lee Francisco, Campana Charles F, Haltiwanger Curtis, Abney Kent, Pannell Keith H
Department of Chemistry, University of Texas at El Paso, El Paso, Texas 79968, USA.
Inorg Chem. 2006 Mar 6;45(5):2203-8. doi: 10.1021/ic051274w.
The reaction between Ta(OEt)5 and 1,1,3,3-tetramethyl-1,3-disiloxanediol, (HOSiMe2OSiMe2OH), leads to new siloxy complexes in which the dimeric nature of Ta(OEt)5 is maintained with both bridging ethoxide and disiloxanediolato bridges. With equal amounts of the reagents, two terminal OEt groups are replaced to form [Ta(OEt)2]2(mu-OEt)2(mu-OSiMe2OSiMe2O)2, 1, whereas with an excess of diol, the remaining terminal OEt groups are also replaced but with a trisiloxanediolato unit to form [Ta(OSiMe2OSiMe2OSiMe2O)]2(mu-OEt)2(mu-OSiMe2OSiMe2O)2, 2. Complexes 1 and 2 catalyze the transformation of HOSiMe2OSiMe2OH to polysiloxanes. Thermal treatment of 1 results in the formation of a 1:2 mixture of Ta2O5/SiO2; no new phases are observed. The molecular structures of 1 and 2 are confirmed by X-ray crystallography.
五乙氧基钽（Ta(OEt)5）与1,1,3,3 - 四甲基 - 1,3 - 二硅氧烷二醇（HOSiMe2OSiMe2OH）之间的反应生成了新的硅氧基配合物，其中Ta(OEt)5的二聚体性质通过桥连的乙氧基和二硅氧烷二醇盐桥得以保持。当试剂等量时，两个末端的乙氧基被取代，形成[Ta(OEt)2]2(μ - OEt)2(μ - OSiMe2OSiMe2O)2，即化合物1；而当二醇过量时，其余的末端乙氧基也被取代，但形成了一个三硅氧烷二醇盐单元，从而形成[Ta(OSiMe2OSiMe2OSiMe2O)]2(μ - OEt)2(μ - OSiMe2OSiMe2O)2，即化合物2。化合物1和2催化HOSiMe2OSiMe2OH转化为聚硅氧烷。对化合物1进行热处理会生成Ta2O5/SiO2的1:2混合物；未观察到新相。化合物1和2的分子结构通过X射线晶体学得以确认。
