A theoretical study of an unusual Y-shaped three-coordinate Pt complex: Pt(0) σ-disilane complex or Pt(II) disilyl complex?
A theoretical study of an unusual Y-shaped three-coordinate Pt complex: Pt(0) σ-disilane complex or Pt(II) disilyl complex?
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DOI：
10.1021/ja304110h
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发表时间：
2012-07
影响因子：
15
通讯作者：
Nozomi Takagi;S. Sakaki
中科院分区：
文献类型：
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作者：
Nozomi Takagi;S. Sakaki
最近报道的三配位Pt配合物Pt[NHC（Dip）（2）]（SiMe（2）Ph）（2）（NHC = N-杂环卡宾; Dip = 2，6-二异丙基苯基）的不寻常Y形结构被认为是还原消除的快照乙硅烷。密度泛函理论的研究表明，这种结构来自于极σ-施主卡宾和甲硅烷基配体的强反式影响。虽然该配合物可以理解为由于Jahn-Teller效应而具有扭曲几何形状的Pt（II）二甲硅烷基配合物，但其（195）Pt NMR化学位移与Pt（II）配合物的化学位移显著不同，但接近于典型Pt（0）配合物的化学位移。它的Si···Si键相互作用约为Si-Si单键通常能量的50%。Pt中心和（SiMe（2）Ph）（2）部分之间的相互作用可以理解为Si-Si σ-键和σ*-反键分子轨道与Pt中心的施主和反馈相互作用。因此，我们得出结论，这可能是Pt（0）σ-乙硅烷络合物，因此是在发生从乙硅烷到Pt中心的相当大量的电荷转移之后的快照。苯基阴离子（Ph（-））和[R-Ar]（-）[R-Ar = 2，6-（2，6-iPr（2）C（6）H（3））（2）C（6）H（3）]以及二价碳（0）配体C（NHC）（2）也提供类似的不寻常的Y形结构。三坐标digermyl，diboryl，和甲硅烷基-硼基络合物的Pt和二甲硅烷基络合物的Pd理论上预测具有类似的不寻常的Y形结构时，强烈捐赠的配体坐标的金属中心。在三角双锥Ir二甲硅基配合物[Ir{NHC（Dip）（2）}（PH（3））（2）（SiMe（3））（2）]（+）中，赤道面也具有类似的不寻常的Y形结构。这些结果表明，Ge-Ge、B-B和B-Si σ键的还原消除可以表现出不同的快拍。
The unusual Y-shaped structure of the recently reported three-coordinate Pt complex Pt[NHC(Dip)(2)](SiMe(2)Ph)(2) (NHC = N-heterocyclic carbene; Dip = 2,6-diisopropylphenyl) was considered a snapshot of the reductive elimination of disilane. A density functional theory study indicates that this structure arises from the strong trans influence of the extremely σ-donating carbene and silyl ligands. Though this complex can be understood to be a Pt(II) disilyl complex bearing a distorted geometry due to the Jahn-Teller effect, its (195)Pt NMR chemical shift is considerably different from those of Pt(II) complexes but close to those of typical Pt(0) complexes. Its Si···Si bonding interaction is ~50% of the usual energy of a Si-Si single bond. The interaction between the Pt center and the (SiMe(2)Ph)(2) moiety can be understood in terms of donation and back-donation interactions of the Si-Si σ-bonding and σ*-antibonding molecular orbitals with the Pt center. Thus, we conclude that this is likely a Pt(0) σ-disilane complex and thus a snapshot after a considerable amount of the charge transfer from disilane to the Pt center has occurred. Phenyl anion (Ph(-)) and [R-Ar](-) [R-Ar = 2,6-(2,6-iPr(2)C(6)H(3))(2)C(6)H(3)] as well as the divalent carbon(0) ligand C(NHC)(2) also provide similar unusual Y-shaped structures. Three-coordinate digermyl, diboryl, and silyl-boryl complexes of Pt and a disilyl complex of Pd are theoretically predicted to have similar unusual Y-shaped structures when a strongly donating ligand coordinates to the metal center. In a trigonal-bipyramidal Ir disilyl complex [Ir{NHC(Dip)(2)}(PH(3))(2)(SiMe(3))(2)](+), the equatorial plane has a similar unusual Y-shaped structure. These results suggest that various snapshots can be shown for the reductive eliminations of the Ge-Ge, B-B, and B-Si σ-bonds.