Synthesis and Reactivity of Thermally Stable Zirconocene (II) Species Precursors

研究了三(吲哚)氢化锆络合物与不同的炔烃的反应，并评价了该锆络合物的反应性。三(吲哚)氢化锆与内炔反应，高产率地得到相应的锆环戊二烯。有趣的是，与末端芳烃的反应生成了高选择性的2，5-二芳基锆环，这样得到的双(吲哚)锆环戊二烯与四氯化钛反应，通过二烯部分与吲基配体的偶联得到了相应的荧衍生物。该反应适用于烷基或芳基取代的双环锆环戊二烯，并提供了取代的荧烯。具有取代环戊二烯配体的锆环戊二烯也被用于反应，并提供了相应的吲哚衍生物。锆环戊二烯的结构参数与相关化合物的结构参数比较表明，吲哚或环戊二烯配体与锆环戊二烯的二烯基团之间的距离对偶联反应活性有很大影响。活性最强的钛环戊二烯的距离最短。此外，反应活性随配体的空间体积增大而增加。四氯化钛在反应中起着重要的氧化剂作用。

Reactions of tris (indenyl) zirconium hydride with a variety of alkynes were investigated and evaluated the reactivity of the zirconium complex as zirconocen (II) equivalent. The reaction of tris (indenyl) zirconium hydride with internal alkynes afforded the corresponding zirconacyclopentadienes in high yields. Interestingly, the reaction with terminal arylalkynes produced the2,5-diarylzirconacycles with high selectivity.A reaction of thus obtained bis (indenyl) zirconacyclopentadienes with titanium tetrachloride afforded the corresponding fluorene derivatives via coupling of the diene moiety with the indenyl ligand. This reaction was applicable for alkyl-or aryl-substituted, and bicyclic zirconacyclopentadienes and furnished the substituted fluorenes. Instead of the indenyl ligand, zirconacyclopentadienes having substituted cyclopentadienyl ligands were also applied for the reaction and afforded the corresponding indene derivatives. A comparison of the structural parameters of the zirconacyclopentadienes with the related ones suggested that the coupling reactivity was strongly affected by the distance between the indenyl or cyclopentadienyl ligands and the diene moiety of the zirconacyclopentadienes. The most reactive titanacyclopentadienes have the shortest distance. In addition, the reactivity was increased with increasing the steric bulkiness of the ligand. Titanium tetrachloride played an important role as an oxidant in the reaction.