Organisch-Chemisches Institut, Universität Münster, Corrensstrasse 40, D-48149 Münster, Germany.
J Am Chem Soc. 2013 May 1;135(17):6465-76. doi: 10.1021/ja3110076. Epub 2013 Apr 17.
The metallocene cation complex Cp*2ZrCH3B(C6F5)4 inserts the phosphino-substituted alkyne Ph-C≡C-PPh2 into the [Zr]-CH3 bond to form the internally phosphane-stabilized cation Cp*2Zr-C(═CMePh)PPh2 (10). Complex 10 adds alkyl isocyanides as well as pivalonitrile at a lateral site at the bent metallocene wedge with retention of the Zr-P bond. Complex 10 acts as a reactive frustrated Lewis pair toward heterocumulenes, undergoing Zr(+)/P addition reactions to the carbonyl groups of an alkyl isocyanate and of carbon dioxide to form the respective five-membered metallaheterocyclic adducts 13 and 14. With mesityl azide complex 10 undergoes a Zr(+)/P FLP N,N-addition reaction at the terminal azide nitrogen atom to form the four-membered FLP cycloadduct 15. The Zr(+)/P FLP is a reactive hydrogen activator. In a stoichiometric reaction it generates a hydridozirconocene cation that subsequently serves as a hydrogenation catalyst for various olefinic or acetylenic substrates. The Zr(+)/P pair 10 undergoes selective 1,4-addition reactions to conjugated enones and to a conjugated ynone to give the corresponding seven-membered metallacyclic Zr(+)/P FLP addition products. Many compounds of this study were characterized by X-ray diffraction.
茂金属阳离子配合物 Cp*2ZrCH3B(C6F5)4 将膦取代的炔烃 Ph-C≡C-PPh2 插入 [Zr]-CH3 键中，形成内部膦稳定的阳离子 Cp*2Zr-C(═CMePh)PPh2 (10)。配合物 10 在弯曲茂金属楔的外侧位置添加烷基异氰化物以及特戊腈，同时保留 Zr-P 键。配合物 10 作为一种反应性受阻路易斯对，与杂cumulenes 发生 Zr(+)/P 加成反应，形成相应的五元金属杂环加合物 13 和 14。与均三甲苯叠氮化物配合物 10 发生 Zr(+)/P FLP N,N-加成反应，在末端叠氮氮原子上形成四元 FLP 环加成物 15。Zr(+)/P FLP 是一种反应性的氢活化剂。在计量反应中，它会生成一个氢锆阳离子，随后该阳离子可作为各种烯烃或炔烃底物的加氢催化剂。Zr(+)/P 对 10 发生对共轭烯酮和共轭 ynone 的选择性 1,4-加成反应，得到相应的七元金属环化 Zr(+)/P FLP 加成产物。本研究中的许多化合物都通过 X 射线衍射进行了表征。
