Laboratorium fur Organische Chemie, Eidgenössische Technische Hochschule ETH Zurich, Wolfgang-Pauli-Strasse 10, Zurich CH-8093, Switzerland.
J Am Chem Soc. 2011 Jun 15;133(23):8914-26. doi: 10.1021/ja110405q. Epub 2011 May 23.
We report Pt(II)-to-Au(I) methyl transfer reactions that occur in the gas phase and in solution. The heterobimetallic Pt(II)/Au(I) complexes {[(dmpe)PtMe(2)][AuPR(3)]}(+) (R = Me (2a), Ph (2b), (t)Bu (2c)), observed in the gas phase by means of electrospray ionization, were subjected to collision induced dissociation (CID) from which we could observe Pt-to-Au transmetalation along two reaction pathways involving formation of a Au-Me bond, analogous to those observed for the Pt(II)/Cu(I) complex recently reported. In the first pathway, neutral AuMe is generated with concomitant migration of PR(3) from Au(I) to the Pt(II) center, forming cation (dmpe)PtMe(PR(3)) (R = Me (5a) or Ph (5b)). In the second pathway, the monophosphine stays attached to the gold center, yielding cation (dmpe)PtMe (7) and R(3)PAuMe. Quantitative energy-resolved collision induced dissociation experiments as well as density functional theory (DFT) calculations were used to investigate the potential surface involved in the transmetalation processes. Energy barriers of 22.3 and 47.9 kcal mol(-1) for the two reaction processes of 2b and of 45.4 kcal mol(-1) for the single reaction process of 2c were obtained. Parallel reactivity is observed in THF solution, allowing for a comparison of the product distributions with those observed in the gas phase, and the postulation of simple steric control of the branching ratio between the two pathways. DFT calculations at the M06-2X//BP86/TZP level were in good agreement with the experiments.
我们报告了在气相和溶液中发生的 Pt(II)-to-Au(I) 甲基转移反应。通过电喷雾电离在气相中观察到的异双金属 Pt(II)/Au(I) 配合物{[(dmpe)PtMe(2)][AuPR(3)]}(+)（R = Me（2a），Ph（2b），（t）Bu（2c）），经历了碰撞诱导解离（CID），从中我们可以观察到 Pt-to-Au 转金属反应沿着两条反应途径进行，涉及形成 Au-Me 键，类似于最近报道的 Pt(II)/Cu(I) 配合物。在第一种途径中，中性 AuMe 生成，同时 PR(3)从 Au(I)迁移到 Pt(II)中心，形成阳离子(dmpe)PtMe(PR(3))（R = Me（5a）或 Ph（5b））。在第二种途径中，单膦配体仍附着在金中心上，生成阳离子(dmpe)PtMe（7）和 R(3)PAuMe。使用能量分辨碰撞诱导解离实验和密度泛函理论（DFT）计算来研究涉及转金属化过程的势能面。对于 2b 的两个反应过程和 2c 的单个反应过程，获得了 22.3 和 47.9 kcal mol(-1)的能量势垒。在 THF 溶液中观察到平行反应性，允许将产物分布与气相中观察到的分布进行比较，并提出两种途径之间的分支比受简单空间位阻控制的简单假设。在 M06-2X//BP86/TZP 水平上的 DFT 计算与实验结果吻合良好。
