由酰胺基吡啶配体支撑的三核烷基氢化稀土配合物：合成、结构、C-Si键活化及乙烯聚合催化活性

Trinuclear alkyl hydrido rare-earth complexes supported by amidopyridinato ligands: synthesis, structures, C-Si bond activation and catalytic activity in ethylene polymerization.

作者信息

Lyubov Dmitry M, Cherkasov Anton V, Fukin Georgy K, Ketkov Sergey Yu, Shavyrin Andrey S, Trifonov Alexander A

机构信息

G. A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, 49 Tropinina str., 603950, Nizhny Novgorod, GSP-445, Russia.

出版信息

Dalton Trans. 2014 Oct 14;43(38):14450-60. doi: 10.1039/c4dt00806e.

DOI:10.1039/c4dt00806e

PMID:24983231

Abstract

The reaction of Ap(9Me)Lu(CH2SiMe3)2(thf) (Ap(9Me) = (2,4,6-trimethylphenyl)[6-(2,4,6-triisopropylphenyl)pyridine-2-yl]amido ligand) with two molar equivalents of PhSiH3 affords a trinuclear alkyl-hydrido cluster [(Ap(9Me)Lu)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2]. The analogous reactions with Ap(9Me)Ln(CH2SiMe3)2(thf) (Ln = Y, Yb) are more complex and result in the formation of mixtures of two types of trinuclear alkyl-hydrido complexes [(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] and [(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiH2Ph)(thf)2] differing in the alkyl group. The DFT calculations of [(ApY)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] (Ap = (2,6-diisopropylphenyl)[6-(2,4,6-triisopropylphenyl)pyridine-2-yl]amido ligand) confirm localization of the HOMO on the Ap*-Y(1A)-CH2SiMe3 fragment, thus explaining its enhanced reactivity. Analysis of the electron density distribution reveals the Y-H and H-H bonding interactions in the (Y)3(μ(2)-H)3(μ(3)-H)2 moiety. The NMR studies of diamagnetic complexes [(Ap(9Me)Lu)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] and [(ApY)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] demonstrated that the trinuclear cores are retained in the solution and revealed exchange between μ(3)- and μ(2)-bridging hydrido ligands. Complexes [(ApLn)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2], the cationic yttrium hydrido cluster (Ap*Y)3(μ(2)-H)3(μ(3)-H)2(thf)3 B(C6F5)4 as well as [(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] proved to be active in catalysis of ethylene polymerization under mild conditions.

摘要

Ap(9Me)Lu(CH2SiMe3)2(thf)（Ap(9Me) = (2,4,6 - 三甲基苯基)[6 - (2,4,6 - 三异丙基苯基)吡啶 - 2 - 基]酰胺配体）与两摩尔当量的PhSiH3反应，生成一个三核烷基 - 氢簇[(Ap(9Me)Lu)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2]。与Ap(9Me)Ln(CH2SiMe3)2(thf)（Ln = Y，Yb）的类似反应更为复杂，会生成两种不同烷基的三核烷基 - 氢配合物[(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2]和[(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiH2Ph)(thf)2]的混合物。[(ApY)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2]（Ap = (2,6 - 二异丙基苯基)[6 - (2,4,6 - 三异丙基苯基)吡啶 - 2 - 基]酰胺配体）的密度泛函理论（DFT）计算证实，最高占据分子轨道（HOMO）定域在Ap* - Y(1A) - CH2SiMe3片段上，从而解释了其增强的反应活性。电子密度分布分析揭示了(Y)3(μ(2)-H)3(μ(3)-H)2部分中的Y - H和H - H键相互作用。对抗磁性配合物[(Ap(9Me)Lu)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2]和[(ApY)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2]的核磁共振（NMR）研究表明，三核核心在溶液中得以保留，并揭示了μ(3)-和μ(2)-桥连氢配体之间的交换。配合物[(ApLn)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2]、阳离子钇氢簇(Ap*Y)3(μ(2)-H)3(μ(3)-H)2(thf)3 B(C6F5)4以及[(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2]在温和条件下催化乙烯聚合反应中均表现出活性。