Periyasamy Ganga, Burton Neil A, Hillier Ian H, Vincent Mark A, Disley Helen, McMaster Jonathan, Garner C David
School of Chemistry, University of Manchester, Manchester, UK M13 9PL.
Faraday Discuss. 2007;135:469-88; discussion 489-506. doi: 10.1039/b607144a.
As Jørgensen pointed out in 1966 (Coord. Chem. Rev., 1966, 1, 164), a ligand is to be regarded as 'innocent' if it allows the oxidation state of a metal in a complex to be defined. In this respect, the vast majority of ligands are 'innocent' and, therefore, ligands that are 'non-innocent' have received special attention. Dithiolenes have been regarded as 'non-innocent' ligands since it is possible to consider a ligand of this type to be present in a complex as either: (i) an ene-1,2-dithiolate dianion or (ii) a neutral dithioketone. On this basis, the electronic structure of a dithiolene complex can be described by a set of resonance structures, each of which involves the dithiolene in one of the two forms with the oxidation state of the metal centre being adjusted accordingly. The relative importance of these structures is expected to be reflected in the corresponding molecular structure and spectroscopic properties. In this paper we present a theoretical study of the pair of related 5-cyclopentadienyl cobalt dithiolene complexes, [CpCo(S2C2(H)Ph)] and [CpCo(S2C2(H)Ph)(PMe3)]. Density functional theory calculations successfully predict their different structures and NMR chemical shifts, which we have measured. These wavefunctions have been analysed, particularly in terms of Natural Bond Orbitals and Nucleus Independent Chemical Shifts in an attempt to understand how "innocence" or otherwise is reflected in the experimental data. To this end, a similar analysis is applied to the gold complexes [Au(S2C2(H)Ph)2] and [Au(S2C2(H)Ph)2].
正如约根森在1966年指出的那样（《配位化学评论》，1966年，第1卷，第164页），如果一种配体能够确定配合物中金属的氧化态，那么它就被视为“无害的”。在这方面，绝大多数配体都是“无害的”，因此，“非无害的”配体受到了特别关注。二硫纶一直被视为“非无害的”配体，因为可以认为这种类型的配体在配合物中以以下两种形式之一存在：（i）烯-1,2-二硫醇二价阴离子或（ii）中性二硫酮。在此基础上，二硫纶配合物的电子结构可以用一组共振结构来描述，其中每一个共振结构都涉及二硫纶以两种形式之一存在，同时金属中心的氧化态也相应调整。这些结构的相对重要性预计会反映在相应的分子结构和光谱性质中。在本文中，我们对一对相关的5-环戊二烯基钴二硫纶配合物[CpCo(S2C2(H)Ph)]和[CpCo(S2C2(H)Ph)(PMe3)]进行了理论研究。密度泛函理论计算成功地预测了它们不同的结构和核磁共振化学位移，这些我们都已测量。我们对这些波函数进行了分析，特别是从自然键轨道和核独立化学位移的角度，试图理解“无害性”或其他性质是如何在实验数据中体现的。为此，我们对金配合物[Au(S2C2(H)Ph)2]和[Au(S2C2(H)Ph)2]进行了类似的分析。
