Versatile Scorpionates and New Developments in the Denticity Changes of NNCp Hybrid Scorpionate/Cyclopentadienyl Ligands in Sc and Y Compounds: From κ1-Nη5-Cp to 

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• 作者：Antonio Otero ; Juan Ferna&#x301 ; ndez-Baeza ; Agusti&#x301 ; n Lara-Sa&#x301 ; nchez ; Antonio Antiñ ; olo ; Juan Tejeda ; Emilia Marti&#x301 ; nez-Caballero ; Isabel Ma&#x301 ; rquez-Segovia ; Isabel Lo&#x301 ; p
• 刊名：Inorganic Chemistry
• 出版年：2008
• 出版时间：June 2, 2008
• 年：2008
• 卷：47
• 期：11
• 页码：4996 - 5005
• 全文大小：1523K
• 年卷期：v.47,no.11(June 2, 2008)
• ISSN：1520-510X

文摘

Reaction of hybrid scorpionate/cyclopentadienyl ligands in the form of the lithium derivatives [Li(bpzcp)(THF)] [bpzcp = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethylcyclopentadienyl], [Li(bpztcp)(THF)] [bpztcp = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-tert-butylethylcyclopentadienyl], and the in situ-generated “Li(bpzpcp)” [bpzpcp = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-phenylethylcyclopentadienyl] with MCl₃(THF)₃ afforded the group 3 halide compounds [MCl₂(bpzcp)(THF)] (M = Sc, 1; Y, 2), [MCl₂(bpztcp)(THF)] (M = Sc, 3; Y, 4), and [MCl₂(bpzpcp)(THF)] (M = Sc, 5; Y, 6). The H₂O adduct of 4, [YCl₂(bpztcp)(H₂O)] (7), was formed when a solution of 4 was allowed to stand at room temperature in the presence of moisture. Complexes 1−7 adopt a pseudo-octahedral structure with heteroscorpionate ligands κ²-NNη⁵-Cp coordinated to the metal through the cyclopentadienyl group and two imino nitrogens of pyrazole rings. The alkyl heteroscorpionate scandium and yttrium complexes recently reported by our group, [M(CH₂SiMe₃)₂(bpzcp)], react with 2,6-dimethylphenol and 3,5-dimethylphenol to give the bis(aryloxide) derivatives [M(OAr)₂(bpzcp)] (M = Sc, OAr = 2,6-dimethylphenoxide, 8; M = Y, OAr = 2,6-dimethylphenoxide, 9; M = Y, OAr = 3,5-dimethylphenoxide, 10). Complex 9 underwent an interesting hydrolysis process to give the tetranuclear complex [{Y(bpzcp)}(μ-OH)₂(μ₃-OH){Y(OAr)₂}]₂ (11). Variable-temperature ¹H NMR experiments on 9 and 10 revealed a rapid fluxional exchange between coordinated and noncoordinated pyrazolyl rings, producing interconversion between the two enantiomers in which the scorpionate ligand can be coordinated in a κ¹-Nη⁵-Cp form. The structures of the complexes were determined by spectroscopic methods and the X-ray crystal structures of 2, 7, and 11 were also established. Complexes 1 and 2 are active olefin polymerization catalysts after activation with methylaluminoxane. These compounds gave atactic polystyrenes with narrow molecular weight distribution (M_n/M_w 1.26−1.91) and with low molecular weights.