Ott Sascha, Borgström Magnus, Kritikos Mikael, Lomoth Reiner, Bergquist Jonas, Akermark Björn, Hammarström Leif, Sun Licheng
Departments of Organic Chemistry and Structural Chemistry, Arrhenius Laboratory, Stockholm University, S-10691 Stockholm, Sweden.
Inorg Chem. 2004 Jul 26;43(15):4683-92. doi: 10.1021/ic0303385.
A model of the iron hydrogenase active site with the structure [(mu-ADT)Fe2(CO)6] (ADT = azadithiolate (S-CH2-NR-CH2-S), (2: R = 4-bromophenyl, 3: R = 4-iodophenyl)) has been assembled and covalently linked to a [Ru(terpy)2]2+ photosensitizer. This trinuclear complex 1 represents one synthetic step toward the realization of our concept of light-driven proton reduction. A rigid phenylacetylene tether has been incorporated as the linking unit in 1 in order to prolong the lifetime of the otherwise short-lived [Ru(terpy)2]2+ excited state. The success of this strategy is demonstrated by comparison of the photophysical properties of 1 and of two related ruthenium complexes bearing acetylenic terpyridine ligands, with those of [Ru(terpy)2]2+. IR and electrochemical studies reveal that the nitrogen heteroatom of the ADT bridge has a marked influence on the electronic properties of the [Fe2(CO)6] core. Using the Rehm-Weller equation, the driving force for an electron transfer from the photoexcited *[Ru(terpy)2]2+ to the diiron site in 1 was calculated to be uphill by 0.59 eV. During the construction of the trinuclear complex 1, n-propylamine has been identified as a decarbonylation agent on the [(mu-ADT)Fe2(CO)6] portion of the supermolecule. Following this procedure, the first azadithiolate-bridged dinuclear iron complex coordinated by a phosphine ligand [(mu-ADT)Fe2(CO)5PPh3] (4, R = 4-bromophenyl) was synthesized.
已组装出一种铁氢化酶活性位点模型，其结构为[(μ - ADT)Fe₂(CO)₆]（ADT = 氮杂二硫醇盐（S - CH₂ - NR - CH₂ - S），(2: R = 4 - 溴苯基，3: R = 4 - 碘苯基）），并将其与[Ru(terpy)₂]²⁺光敏剂共价连接。这种三核配合物1代表了朝着实现我们光驱动质子还原概念迈出的一个合成步骤。已在1中引入刚性苯乙炔连接单元，以延长原本寿命较短的[Ru(terpy)₂]²⁺激发态的寿命。通过比较1以及两种带有炔基三联吡啶配体的相关钌配合物与[Ru(terpy)₂]²⁺的光物理性质，证明了该策略的成功。红外和电化学研究表明，ADT桥的氮杂原子对[Fe₂(CO)₆]核的电子性质有显著影响。使用雷姆 - 韦勒方程计算得出，光激发的*[Ru(terpy)₂]²⁺向1中双铁位点进行电子转移的驱动力为0.59 eV，是向上的。在构建三核配合物1的过程中，正丙胺被确定为超分子[(μ - ADT)Fe₂(CO)₆]部分的脱羰试剂。按照此程序，合成了第一个由膦配体[(μ - ADT)Fe₂(CO)₅PPh₃]（4，R = 4 - 溴苯基）配位的氮杂二硫醇盐桥连双核铁配合物。
