Otero Antonio, Fernández-Baeza Juan, Lara-Sánchez Agustín, Antiñolo Antonio, Tejeda Juan, Martínez-Caballero Emilia, Márquez-Segovia Isabel, López-Solera Isabel, Sánchez-Barba Luis F, Alonso-Moreno Carlos
Departamento de Química Inorgánica, Orgánica y Bioquímica, Universidad de Castilla-La Mancha, Ciudad Real, Spain.
Inorg Chem. 2008 Jun 2;47(11):4996-5005. doi: 10.1021/ic800267v. Epub 2008 Apr 30.
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 kappa2-NNeta5-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)}(micro-OH)2(micro3-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 kappa1-Neta5-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 (Mn/Mw 1.26-1.91) and with low molecular weights.
锂衍生物形式的杂化蝎形/环戊二烯基配体[Li(bpzcp)(THF)] [bpzcp = 2,2 - 双(3,5 - 二甲基吡唑 - 1 - 基)-1,1 - 二苯乙基环戊二烯基]、[Li(bpztcp)(THF)] [bpztcp = 2,2 - 双(3,5 - 二甲基吡唑 - 1 - 基)-1 - 叔丁基乙基环戊二烯基]以及原位生成的“Li(bpzpcp)”[bpzpcp = 2,2 - 双(3,5 - 二甲基吡唑 - 1 - 基)-1 - 苯乙基环戊二烯基]与MCl3(THF)3反应，得到了第3族卤化物化合物[MCl2(bpzcp)(THF)] (M = Sc, 1; Y, 2)、[MCl2(bpztcp)(THF)] (M = Sc, 3; Y, 4)和[MCl2(bpzpcp)(THF)] (M = Sc, 5; Y, 6)。当4的溶液在有水分存在的情况下于室温放置时，形成了4的水加合物[YCl2(bpztcp)(H2O)] (7)。配合物1 - 7具有伪八面体结构，杂化蝎形配体通过环戊二烯基和吡唑环的两个亚氨基氮以κ2 - NNη5 - Cp形式与金属配位。我们小组最近报道的烷基杂化蝎形钪和钇配合物[M(CH2SiMe3)2(bpzcp)]与2,6 - 二甲基苯酚和3,5 - 二甲基苯酚反应，得到双(芳氧基)衍生物[M(OAr)2(bpzcp)] (M = Sc, OAr = 2,6 - 二甲基苯氧基, 8; M = Y, OAr = 2,6 - 二甲基苯氧基, 9; M = Y, OAr = 3,5 - 二甲基苯氧基, 10)。配合物9经历了一个有趣的水解过程，生成四核配合物[{Y(bpzcp)}(μ - OH)2(μ3 - OH){Y(OAr)2}]2 (11)。对9和10进行的变温1H NMR实验表明，配位和未配位的吡唑环之间存在快速的动态交换，导致两种对映体之间发生相互转化，其中蝎形配体可以以κ1 - Nη5 - Cp形式配位。通过光谱方法确定了配合物的结构，还确定了2、7和11的X射线晶体结构。配合物1和2在用甲基铝氧烷活化后是活性烯烃聚合催化剂。这些化合物得到了无规聚苯乙烯，其分子量分布窄(Mn/Mw 1.26 - 1.91)且分子量低。
