三芳基硅烷醇盐是用于炔复分解的钼亚烷基催化剂的优先辅助配体,但在钨系列中导致令人失望的结果和较差的稳定性。1 H, 183 W 异核多重键相关光谱,利用183 W 中心与烷叉帽上的外围质子之间有利的5 J耦合,揭示了这些配体将路易斯酸度上调到一定程度,使得环丁二烯钨在最初形成[2+2]环加成步骤过度稳定并且催化周转停止。以183 W NMR 位移作为中心原子路易斯酸度的代表,并通过烷叉单元的化学位移张量分析,重新审视了配体设计,并制备了更强的 π 供体全醇盐配体。新的膨胀螯合物具有缓和的路易斯酸度,并且在速率和官能团相容性方面优于带有单齿叔丁氧基配体的经典Schrock催化剂。
“Canopy Catalysts” for Alkyne Metathesis: Molybdenum Alkylidyne Complexes with a Tripodal Ligand Framework
作者:Julius Hillenbrand、Markus Leutzsch、Ektoras Yiannakas、Christopher P. Gordon、Christian Wille、Nils Nöthling、Christophe Copéret、Alois Fürstner
DOI:10.1021/jacs.0c04742
日期:2020.6.24
certain stability toward water, which marks a big leap forward in metal alkylidyne chemistry in general. At the same time, they tolerate many donor sites, including basic nitrogen and numerous heterocycles. This aspect is substantiated by applications to polyfunctional (natural) products. A combined spectroscopic, crystallographic, and computational study provides insights into structure and electronic