ヒドロゲナーゼ活性中心のモデル構築をめざしたニッケルー鉄二核錯体の合成と反応

为了阐明[NiFe]氢酶介导的二氢活化过程，我参与了该酶催化过程中可能存在的中间产物的模型研究。合成了一系列新的双金属桥联镍铁(羰基/氰化物)配合物，[(18-Crown-6)K]2[(CO)(CN)2Fe(pdt)Ni(CO)(PPh3)](1；Pdt=丙烷-1，3-二硫酸酯)，[(18-冠-6)K]2[(CO)(CN)2Fe(Ndt)-Ni(CO)(PPh3)](2；Ndt=降硼烷外-2，3-二硫代硫酸酯)和m-氢化物配合物[(18-冠-6)K][(CN)(CO)2Fe(Pdt)(Mu-H)-Ni(CN)(PCy3)](3)，作为Ni-L和Ni-R态的模型。用Ni(PPh_3)_4与Fe(II)硫醇配合物[(CO)_2(CN)_2Fe(PDT)](2-)和[(CO)_2(CN)_2Fe(NDT)](2-)反应合成了Fe(II)-Ni(0)络合物1和2。通过Fe(II)硫醇配合物与Ni(II)-氢化物配合物Ni(H)(Cl)(PCy3)2的类似反应得到了金属氢化物配合物3。配合物1和2的Ni-Fe距离为~2.5A，因此它们是一种新型的合成模型化合物，具有天然的Ni-L状态和Ni中心保持的四面体几何构型。金属氢化物双金属络合物3的Ni-Fe距离约为2.6A，是[Ni-Fe]加氢酶催化循环中非常重要的中间模型络合物，被称为Ni-R态，其中Fe被CO/CN配位，Ni具有扭曲的四面体构型。Ruchfuss报道了一个含Lewis酸保护CN配体的模型配合物，而配合物3是第一个Ni-Fe(CO/CN)金属氢化物配合物。

For the purpose to elucidate the dihydrogen activation process mediated by [NiFe] hydrogenase, I was engaged in the model study of plausible intermediates associated during catalysis by the enzyme. A series of new heterobimetallic dithiolate-bridged Ni-Fe(carbonyl/cyanide) complexes, [(18-Crown-6)K]2[(CO)(CN)2Fe(pdt)Ni(CO)(PPh3)] (1; pdt = propane-1,3-dithiolate), [(18-Crown-6)K]2[(CO)(CN)2Fe(ndt)- Ni(CO)(PPh3)] (2; ndt = norborane-exo-2,3-dithiolate), and the m-hydride complex [(18-Crown-6)K][(CN)(CO)2Fe(pdt)(mu-H)- Ni(CN)(PCy3)] (3), were synthesized as models of the different states named Ni-L and Ni-R states. The Fe(II)-Ni(0) complexes 1 and 2 were synthesized by the reaction of Ni(PPh3)4 with Fe(II) thiolato complexes [(CO)2(CN)2Fe(pdt)](2-) and [(CO)2(CN)2Fe(ndt)](2-), respectively. The mu-hydride complex 3 was obtained via a similar reaction of the Fe(II) thiolato complex with Ni(II)-hydride complex Ni(H)(Cl)(PCy3)2. Complexes 1 and 2 has Ni-Fe distances of ~2.5 A, and thus they serve as the novel synthetic model complexes native Ni-L state and Ni center retain tetrahedral geometry. The mu-hydride bimetallic complex 3 with Ni-Fe distance ~2.6 A represents the very important intermediate model complex in the catalytic cycle of [Ni-Fe] hydrogenase termed as Ni-R state where Fe is coordinated by CO/CN and the Ni possesses a distorted tetrahedral geometry. While a model complex having CN ligand protected with Lewis acid was reported by Rauchfuss, complex 3 is the first Ni-Fe (CO/CN) mu-hydride complex.