含末端及橋接咪唑配位基之單核與雙核鎳-硫錯合物：鎳-鐵氫化酵素之鎳活性中心

Mononuclear and Dinuclear Nickel-Thiolate Complexes Containing Terminal and Bridging Imidazole/Imidazolate Ligand：Relevance to the Nickel site of [NiFe] Hydrogenases

賴冠廷(Kuan-Ting Lai)

指導教授 ： 廖文峯

國立清華大學/理學院/化學系/碩士(2009年)

摘要

Complex [PPN][{Ni(P(o-C6H3-3-SiMe3-2-S)3)}2(C3H3N2)] (1) was synthesized by reaction of [PPN][NiIII(Cl)(P(o-C6H3-3-SiMe3-2-S)3)] and [Na][Im] in 1:1 moalr ratio in THF solution. Complex 1 was an asymmetry of the imidazolate-bridged dinuclear nickel(III) complex, and the geometry of the Ni center is a five-coordinate distorted trignoal bipyramidal.
A THF solution of 2,6-lutidine–HBF4 was added dropwise to a THF solution of complex 1 at room temperature under a N2 atmosphere to yield [NiIII(C3H4N2)(P(o-C6H3-3-SiMe3-2-S)3)] (2). The reaction of [PPN][BH4] and [NiIII(C3H4N2)(P(o-C6H3-3-SiMe3-2-S)3)] in 1:1 moalr ratio in THF-CH3CN solution led to [PPN][NiII(C3H4N2)(P(o-C6H3-3-SiMe3-2-S)3)] (3). Single-crystal X-ray structures of complexes 2 and 3 are essentially isostructural.
The complex 2 could not undergo reductive elimination under CO atomosphere to produce [PPN][NiII(CO)(P(o-C6H3-3-SiMe3-2-S)3)] because of the terminal imidazole ligand of complex 2 is a poor electron donating ligand, and the Ni(III) center of complex 2 is electron deficient. However, complex 3 could undergo ligand displacement reaction with exogenous CO to generate [PPN][NiII(CO)(P(o-C6H3-3-SiMe3-2-S)3)].

關鍵字

咪唑配位基 ； 鎳-鐵氫化酵素 ； 雙核鎳-硫錯合物 ； 單核鎳-硫錯合物 ； 橋接咪唑配位基

並列摘要

以1：1的比例將[PPN][NiIII(Cl)(P(o-C6H3-3-SiMe3-2-S)3)]和[Na][Im]溶於
THF-CH3CN中，生成[PPN][{Ni(P(o-C6H3-3-SiMe3-2-S)3)}2(C3H3N2)] (1)，化合物1屬於不對稱Ni雙核的imidaolate橋接化合物，其兩個Ni金屬中心皆為五配位扭曲的雙三角錐結構。
以微量針筒取2,6-lutidine與HBF4溶於10 ml THF中，於室溫、氮氣下慢慢滴加至化合物1，形成[NiIII(C3H4N2)(P(o-C6H3-3-SiMe3-2-S)3)] (2)。以等比例[NiIII(C3H4N2)(P(o-C6H3-3-SiMe3-2-S)3)]、[PPN][BH4]溶在THF-CH3CN中，還原成[PPN][NiII(C3H4N2)(P(o-C6H3-3-SiMe3-2-S)3)] (3)。由晶體結構知化合物2與化合物3為重要的isostructure皆為五配位扭曲的雙三角錐結構。
化合物2其imidazole ligand為供給電子能力較弱的配位子，Ni(III)中心缺電子，在CO的環境下無法行還原脫去產生[PPN][NiII(CO)(P(o-C6H3-3-SiMe3-2-S)3)]
化合物，化合物3則在CO的環境下可直接作配位子的取代反應產生[PPN][NiII(CO)(P(o-C6H3-3-SiMe3-2-S)3)]。

並列關鍵字

imidazole ligand ； NiFe hydrogenase ； Dinuclear Nickel-Thiolate complex ； mononuclear Nickel-Thiolate complex ； bridging imidazolate ligand

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