Noninnocence in Metal Complexes: A Dithiolene Dawn
Noninnocence in Metal Complexes: A Dithiolene Dawn
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DOI：
10.1021/ic2011748
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发表时间：
2011-10-17
影响因子：
4.6
通讯作者：
Gray, Harry B.
中科院分区：
文献类型：
--
作者：
Eisenberg, Richard;Gray, Harry B.
无机化学的非纯真可以追溯到半个世纪前对含有不饱和二硫醇盐配体的金属络合物所做的研究。在 20 世纪 60 年代初期，三个不同研究小组的一系列活动中，合成了这些配体的均配 his 和 tris 配合物（后来被称为二硫烯），并研究了它们的结构、电化学、光谱和磁性。这些配合物以容易的单电子转移和溶液中的强烈颜色而著称，而传统的氧化态描述无法解释它们的电子结构。一般来说，他的配合物被发现是方形平面的，包括顺磁配合物和不同形式的 d(n) 配置的这种几何形状的第一个例子。一些中性和单阴离子三配合物被发现具有三棱柱配位，这是第一次在分子金属配合物中观察到这种几何形状。采用扩展休克尔和其他半经验计算方法的电子结构计算揭示了这些系统的前沿轨道中广泛的配体金属混合，包括观察到填充的金属基轨道比相同类型的配体基轨道更稳定的结构，这表明氧化或还原时的单电子变化发生在配体上而不是金属中心。对这项早期工作进行了总结，随后简要介绍了基于更先进的光谱和计算方法对这些系统的当前解释。最重要的信息是，早期的工作确实为后续含有氧化还原活性配体的金属配合物的研究奠定了坚实的基础。
Noninnocence in inorganic chemistry traces its roots back half a century to work that was done on metal complexes containing unsaturated dithiolate ligands. In a flurry of activity in the early 1960s by three different research groups, homoleptic his and tris complexes of these ligands, which came to be known as dithiolenes, were synthesized, and their structural, electrochemical, spectroscopic, and magnetic properties were investigated. The complexes were notable for facile one-electron transfers and intense colors in solution, and conventional oxidation-state descriptions could not account for their electronic structures. The his complexes were, in general, found to be square-planar, including the first examples of this geometry for paramagnetic complexes and different formal d(n) configurations. Several of the neutral and monoanionic tris complexes were found to have trigonal-prismatic coordination, the first time that this geometry had been observed in molecular metal complexes. Electronic structural calculations employing extended Huckel and other semiempirical computational methods revealed extensive ligand metal mixing in the frontier orbitals of these systems, including the observation of structures in which filled metal-based orbitals were more stable than ligand-based orbitals of the same type, suggesting that the one-electron changes upon oxidation or reduction were occurring on the ligand rather than on the metal center. A summary of this early work is followed with a brief section on the current interpretations of these systems based on more advanced spectroscopic and computational methods. The take home message is that the early work did indeed provide a solid foundation for what was to follow in investigations of metal complexes containing redox-active ligands.