Matsuo Tsukasa, Kawaguchi Hiroyuki
Coordination Chemistry Laboratories, Institute for Molecular Science, and CREST, Japan Science and Technology Corporation (JST), Myodaiji, Okazaki 444-8585, Japan.
Inorg Chem. 2002 Nov 18;41(23):6090-8. doi: 10.1021/ic025882c.
The preparation and characterization of a series of niobium(V) complexes that incorporate the linear-linked aryloxide trimers 2,6-bis(4,6-dimethylsalicyl)-4-tert-butylphenol [H3(Me-L)] and 2,6-bis(4-methyl-6-tert-butylsalicyl)-4-tert-butylphenol [H3(tBu-L)] are described. The chloride complex [Nb(Me-L)Cl2]2 (1) was prepared in high yield by reaction of NbCl5 with H3(Me-L) in toluene. In contrast, the analogous reaction with H3(tBu-L) gave a mixture of [Nb(tBu-L)Cl2]2 (2) and [Nb(de-tBu-L)Cl2]2 (3a). During the formation of 3a, one of tert-butyl groups at the ortho position in the tBu-L ligand was lost. When the NbCl5/H3(tBu-L) reaction was carried out in acetonitrile, Nb[H(tBu-L)]Cl3(NCMe) (4) was obtained. Heating a solution of 4 in toluene generated 2 and 3a. The isolated complex 4 underwent ligand redistribution in acetonitrile to produce Nb[H(tBu-L)]2Cl(NCMe) (5). Treatment of NbCl5 with Li3(tBu-L) in toluene afforded 2. The chloride ligands in 1 and 2 smoothly reacted with 4 equiv of MeMgI and LiStBu, resulting in [Nb(R-L)Me2]2 [R = Me (6), tBu (7)] and Nb(Me-L)(StBu)2 (8), respectively. A number of the above complexes have been characterized by X-ray crystallography. In the structures of 1, 2, and 6, the R-L ligand is bound to the metal center with a U-coordination mode, while an alternative S-conformation is adopted for 3a and 8. Complexes 4 and 5 contain a bidentate H(tBu-L) diphenoxide-monophenol ligand.
描述了一系列包含线性连接的芳氧基三聚体2,6 - 双(4,6 - 二甲基水杨基)-4 - 叔丁基苯酚[H3(Me - L)]和2,6 - 双(4 - 甲基 - 6 - 叔丁基水杨基)-4 - 叔丁基苯酚[H3(tBu - L)]的铌(V)配合物的制备和表征。通过NbCl5与H3(Me - L)在甲苯中反应以高产率制备了氯化物配合物[Nb(Me - L)Cl2]2(1)。相比之下，与H3(tBu - L)的类似反应得到了[Nb(tBu - L)Cl2]2(2)和[Nb(de - tBu - L)Cl2]2(3a)的混合物。在3a的形成过程中，tBu - L配体邻位的一个叔丁基基团丢失。当在乙腈中进行NbCl5/H3(tBu - L)反应时，得到了Nb[H(tBu - L)]Cl3(NCMe)(4)。在甲苯中加热4的溶液生成了2和3a。分离得到的配合物4在乙腈中发生配体重新分布，生成了Nb[H(tBu - L)]2Cl(NCMe)(5)。在甲苯中用Li3(tBu - L)处理NbCl5得到了2。1和2中的氯配体分别与4当量的MeMgI和LiStBu顺利反应，分别生成了[Nb(R - L)Me2]2[R = Me(6)，tBu(7)]和Nb(Me - L)(StBu)2(8)。上述许多配合物已通过X射线晶体学进行了表征。在1、2和6的结构中，R - L配体以U - 配位模式与金属中心结合，而3a和8则采用了另一种S - 构象。配合物4和5包含一个双齿H(tBu - L)二酚单酚配体。
