Evans William J, Mueller Thomas J, Ziller Joseph W
Department of Chemistry, University of California, Irvine, California 92697-2025, USA.
J Am Chem Soc. 2009 Feb 25;131(7):2678-86. doi: 10.1021/ja808763y.
The limits of steric crowding in tris(pentamethylcyclopentadienyl) complexes have been expanded by isolation of the first compound with this ligand set and two additional ligands, (C(5)Me(5))(3)ML(2). This result was obtained in a study of the effect of added ligands on the reactivity of sterically crowded (C(5)Me(5))(3)La, 1. Although neither THF nor Ph(3)PO formed crystallographically characterizable (C(5)Me(5))(3)LaL(x) complexes with 1, these (C(5)Me(5))(3)La/L(x) mixtures displayed enhanced reactivity compared to 1 with substrates such as C(8)H(8) and CO(2). Attempts to use adamantyl azide, AdN(3), to make (C(5)Me(5))(3)LaL(x) complexes led to the first example of azide insertion into a metal cyclopentadienyl linkage to generate (C(5)Me(5))(2)Laeta(2)-(N,N')-(C(5)Me(5))NN'N''Ad. Addition of Me(3)CCN to 1 produced the first crystallographically characterized (C(5)Me(5))(3)ML(2) complex, (C(5)Me(5))(3)La(NCCMe(3))(2).
通过分离出首例含有这种配体组合及另外两个配体的化合物（C(5)Me(5))(3)ML(2)，三（五甲基环戊二烯基）配合物中空间拥挤的极限得到了扩展。这一结果是在一项关于添加配体对空间拥挤的（C(5)Me(5))(3)La（1）反应活性影响的研究中获得的。尽管四氢呋喃（THF）和三苯基氧化膦（Ph(3)PO）都未与1形成可通过晶体学表征的（C(5)Me(5))(3)LaL(x)配合物，但这些（C(5)Me(5))(3)La/L(x)混合物与1相比，对诸如C(8)H(8)和CO(2)等底物显示出增强的反应活性。尝试使用金刚烷基叠氮化物（AdN(3)）制备（C(5)Me(5))(3)LaL(x)配合物，得到了叠氮化物插入金属环戊二烯基键生成（C(5)Me(5))(2)Laη(2)-(N,N')-(C(5)Me(5))NN'N''Ad的首个实例。向1中加入甲基叔丁基腈（Me(3)CCN），得到了首个通过晶体学表征的（C(5)Me(5))(3)ML(2)配合物（C(5)Me(5))(3)La(NCCMe(3))(2)。
