Chemical Sciences Division, Lawrence Berkeley National Laboratory and Department of Chemistry, University of California , Berkeley, California 94720, United States.
J Am Chem Soc. 2016 Aug 3;138(30):9682-93. doi: 10.1021/jacs.6b05442. Epub 2016 Jul 26.
The scope and mechanism of the microenvironment-catalyzed C(sp(3))-C(sp(3)) reductive elimination from transition metal complexes [Au(III), Pt(IV)] is explored. Experiments detailing the effect of structural perturbation of neutral and anionic spectator ligands, reactive alkyl ligands, solvent, and catalyst structure are disclosed. Indirect evidence for a coordinatively unsaturated encapsulated cationic intermediate is garnered via observation of several inactive donor-arrested inclusion complexes, including a crystallographically characterized encapsulated Au(III) cation. Finally, based on stoichiometric experiments under catalytically relevant conditions, a detailed mechanism is outlined for the dual supramolecular and platinum-catalyzed C-C coupling between methyl iodide and tetramethyltin. Determination of major platinum species present under catalytic conditions and subsequent investigation of their chemistry reveals an unexpected interplay between cis-trans isomerism and the supramolecular catalyst in a Pt(II)/Pt(IV) cycle, as well as several off-cycle reactions.
本文探索了过渡金属配合物[Au(III)，Pt(IV)]中微环境催化的 C(sp(3))-C(sp(3))还原消除的范围和机理。实验详细说明了中性和阴离子 spectator 配体、反应性烷基配体、溶剂和催化剂结构的结构扰动的影响。通过观察几种不活跃的供体捕获的包含配合物，包括结晶学上表征的包含的 Au(III)阳离子，间接获得了配位不饱和的封闭阳离子中间物的证据。最后，根据在催化相关条件下的化学计量实验，概述了在甲基碘和四甲基锡之间的双超分子和铂催化的 C-C 偶联的详细机理。在催化条件下确定存在的主要铂物种，并随后研究其化学性质，揭示了顺反异构和超分子催化剂在 Pt(II)/Pt(IV)循环中的意想不到的相互作用，以及几种非循环反应。
