Donor-free phosphenium-metal(0)-halides with unsymmetrically bridging phosphenium ligands.
Donor-free phosphenium-metal(0)-halides with unsymmetrically bridging phosphenium ligands.
复制标题
具有不对称桥接鏻配体的无供体鏻金属(0)卤化物。
DOI：
10.1021/ic400886b
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发表时间：
2013
影响因子：
4.6
通讯作者：
D. Gudat
中科院分区：
文献类型：
--
作者：
D. Förster;J. Nickolaus;M. Nieger;Z. Benkő;A. Ehlers;D. Gudat
（cod）MCl_2（cod = 1，5-环辛烷，M = Pd，Pt）与N-杂环仲膦或双膦反应生成配合物[（NHP）MCl]_2（NHP = N-杂环膦）。Pd络合物也可从氯膦前体和Pd 2（dba）3获得。单晶X射线衍射研究证实了含有μ-桥连NHP配体的双核配合物以不对称结合模式存在，并显示出金属配位几何形状从扭曲三角形（M = Pd）到T形（M = Pt）的惊人变化。DFT计算模型化合物重现这些结构特征的Pt络合物，但预测一个不寻常的C2 v对称的分子结构与两个不同的金属配位环境的Pd物种。这种结构和实际的中心对称的几何形状之间的偏差是占一个平坦的能量超曲面，这允许在非常低的能量成本的NHP配体的取向的大的扭曲的预测。DFT结果和光谱研究表明，标题化合物应被描述为膦-金属（0）-卤化物，而不是传统的二价金属阳离子的膦配合物，并表明NHP配体接收来自金属的净电荷捐赠，但保留了独特的阳离子特征。非对称的NHP结合模式与两个M-P键中σ-供体/π-受体贡献的不均匀分布有关。初步研究表明，钯配合物与膦供体的反应提供了配体稳定的零价金属原子和金属（0）-卤化物片段的可行来源。
Reactions of (cod)MCl2 (cod = 1,5 cyclooctadiene, M = Pd, Pt) with N-heterocyclic secondary phosphines or diphosphines produced complexes [(NHP)MCl]2 (NHP = N-heterocyclic phosphenium). The Pd complex was also accessible from a chlorophosphine precursor and Pd2(dba)3. Single-crystal X-ray diffraction studies established the presence of dinuclear complexes that contain μ-bridging NHP ligands in an unsymmetrical binding mode and display a surprising change in metal coordination geometry from distorted trigonal (M = Pd) to T-shaped (M = Pt). DFT calculations on model compounds reproduced these structural features for the Pt complex but predicted an unusual C2v-symmetric molecular structure with two different metal coordination environments for the Pd species. The deviation between this structure and the actual centrosymmetric geometry is accounted for by the prediction of a flat energy hypersurface, which permits large distortions in the orientation of the NHP ligands at very low energetic cost. The DFT results and spectroscopic studies suggest that the title compounds should be described as phosphenium-metal(0)-halides rather than conventional phosphido complexes of divalent metal cations and indicate that the NHP ligands receive net charge donation from the metals but retain a distinct cationic character. The unsymmetric NHP binding mode is associated with an unequal distribution of σ-donor/π-acceptor contributions in the two M-P bonds. Preliminary studies indicate that reactions of the Pd complex with phosphine donors provide a viable source of ligand-stabilized, zerovalent metal atoms and metal(0)-halide fragments.
影响因子：
4.9
作者：
Edge, Ruth;Less, Robert J.;Wright, Dominic S.
通讯作者：
Wright, Dominic S.