Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein-Strasse 29 a, 18059 Rostock, Germany.
J Am Chem Soc. 2010 Mar 31;132(12):4369-80. doi: 10.1021/ja910527w.
The reactivity of variously substituted alkynylsilanes toward selected group 4 metallocene complexes was investigated. Reactions of the alkynylsilanes R(1)C(2)SiR(2)(2)H (R(1) = SiMe(3), R(2) = Me, 1; R(1) = SiMe(3), R(2) = Ph, 2; R(1) = SiMe(2)H, R(2) = Me, 5) with Cp(2)TiMe(2) (Cp = eta(5)-cyclopentadienyl) resulted, upon methyl group transfer to the silyl group, in the previously described titanocene alkyne complexes Cp(2)Ti(R(1)C(2)SiR(2)(2)R(3)) (R(1) = Me(3)Si, R(2) = R(3) = Me, 3; R(1) = HMe(2)Si, R(2) = R(3) = Me, 6) or the unreported complex 4 (R(1) = Me(3)Si, R(2) = Ph, R(3) = Me). The Cp(2)TiCl(2)/n-BuLi system yielded alkyne complexes 6 and 7 (R(1) = HMe(2)Si, R(2) = Me, R(3) = H); no alkyl group transfer was detected. On the other hand, reactions utilizing the Cp(2)ZrCl(2)/n-BuLi system afforded inseparable mixtures; however, complexes of the type Cp(2)Zr[R(1)C(2)SiMe(2)(n-Bu)] (R(1) = Me(3)Si, 8; R(1) = HMe(2)Si, 9) were detected. Cp(2)Hf(n-Bu)(2) reacted with the alkynylsilanes in a diverse way, depending on the substituents of the alkyne substrate. The reaction with an excess of alkyne 1 (R(1) = Me(3)Si, R(2) = Me) afforded only an intractable mixture, which contained Me(3)SiC(2)SiMe(2)(n-Bu) (10). Hafnacyclopentadienes 13-15 as precedented product types were obtained when alkyne 12 (R(1) = Ph, R(2) = Me) was used. In sharp contrast, the symmetrically substituted alkynes 5 (R(1) = HMe(2)Si, R(2) = Me) and H(2)PhSiC(2)SiPhH(2) (18) yielded the hitherto unknown Si-containing metallacycles 16 and 19. A reaction mechanism leading to these products was proposed and subsequently supported by DFT calculations. In addition, the reduction of Cp(2)HfCl(2) with magnesium in THF in the presence of alkynylsilanes was shown to be an alternative route to compounds 14-16 and 19. Presumably due to steric reasons, alkyne 1 could not form any of the product types described above. Nevertheless, it was utilized for the preparation of the PMe(3)-stabilized hafnocene alkyne complex 11.
各种取代的炔基硅烷与选定的第 4 族茂金属络合物的反应性进行了研究。炔基硅烷 R(1)C(2)SiR(2)(2)H (R(1) = SiMe(3), R(2) = Me, 1; R(1) = SiMe(3), R(2) = Ph, 2; R(1) = SiMe(2)H, R(2) = Me, 5) 与 Cp(2)TiMe(2) (Cp = eta(5)-环戊二烯基)反应，在甲基基团转移到硅烷基后，得到了先前描述的钛茂烷炔复合物 Cp(2)Ti(R(1)C(2)SiR(2)(2)R(3)) (R(1) = Me(3)Si, R(2) = R(3) = Me, 3; R(1) = HMe(2)Si, R(2) = R(3) = Me, 6) 或未报道的复合物 4 (R(1) = Me(3)Si, R(2) = Ph, R(3) = Me)。Cp(2)TiCl(2)/n-BuLi 体系产生炔复合物 6 和 7 (R(1) = HMe(2)Si, R(2) = Me, R(3) = H); 未检测到烷基基团转移。另一方面，利用 Cp(2)ZrCl(2)/n-BuLi 体系的反应得到了不可分离的混合物; 然而，检测到了 Cp(2)Zr[R(1)C(2)SiMe(2)(n-Bu)] (R(1) = Me(3)Si, 8; R(1) = HMe(2)Si, 9) 类型的复合物。Cp(2)Hf(n-Bu)(2)与炔基硅烷以不同的方式反应，取决于炔基底物的取代基。与过量炔基 1 (R(1) = Me(3)Si, R(2) = Me)反应仅得到难以处理的混合物，其中包含 Me(3)SiC(2)SiMe(2)(n-Bu) (10)。当使用炔基 12 (R(1) = Ph, R(2) = Me)时，获得了 Hafnacyclopentadienes 13-15 作为先前报道的产物类型。与此形成鲜明对比的是，对称取代的炔基 5 (R(1) = HMe(2)Si, R(2) = Me)和 H(2)PhSiC(2)SiPhH(2) (18)生成了迄今未知的含有硅的金属环戊二烯基复合物 16 和 19。提出了一种导致这些产物的反应机制，并随后通过 DFT 计算得到了支持。此外，在 THF 中，Cp(2)HfCl(2)与镁的还原反应，在炔基硅烷存在下，是化合物 14-16 和 19 的另一种途径。由于空间位阻的原因，炔基 1 不能形成上述任何一种产物类型。然而，它被用于制备 PMe(3)-稳定的 Hafnocene 炔基复合物 11。
