Department of Chemistry, Faculty of Science, Central Tehran Branch, Islamic Azad University, Shahrak Gharb, Tehran, Iran.
Inorg Chem. 2010 Dec 6;49(23):11249-53. doi: 10.1021/ic1020912. Epub 2010 Nov 2.
Ligand effects in bimetallic high oxidation state systems containing a X-Pd-Pd-Y framework have been explored with density functional theory (DFT). The ligand X has a strong effect on the dissociation reaction of Y to form X-Pd-Pd + Y(-). In the model system examined where Y is a weak σ-donor ligand and a good leaving group, we find that dissociation of Y is facilitated by greater σ-donor character of X relative to Y. We find that there is a linear correlation of the Pd-Y and Pd-Pd bond lengths with Pd-Y bond dissociation energy, and with the σ-donating ability of X. These results can be explained by the observation that the Pd d(z(2)) population in the PdY fragment increases as the donor ability of X increases. In these systems, the Pd(III)-Pd(III) arrangement is favored when X is a weak σ-donor ligand, while the Pd(IV)-Pd(II) arrangement is favored when X is a strong σ-donor ligand. Finally, we demonstrate that ligand exchange to form a bimetallic cationic species in which each Pd is six-coordinate should be feasible in a high polarity solvent.
含 X-Pd-Pd-Y 框架的双金属高氧化态体系中的配体效应已通过密度泛函理论（DFT）进行了研究。配体 X 对 Y 的离解反应形成 X-Pd-Pd + Y(-) 有很强的影响。在所研究的模型体系中，Y 是一个弱σ供体配体和一个好的离去基团，我们发现相对于 Y，X 的σ供体性质越强，Y 的离解就越容易。我们发现 Pd-Y 和 Pd-Pd 键长与 Pd-Y 键离解能以及 X 的σ给体能力呈线性相关。这些结果可以通过观察到 PdY 片段中 Pd d(z(2)) 电子密度随着 X 的供体能力增加而增加来解释。在这些体系中，当 X 是弱 σ 供体配体时，Pd(III)-Pd(III)排列是有利的，而当 X 是强 σ 供体配体时，Pd(IV)-Pd(II)排列是有利的。最后，我们证明在高极性溶剂中，形成每个 Pd 都是六配位的双金属阳离子物种的配体交换应该是可行的。
