Department of Chemistry, University of Michigan , 930 N. University, Ann Arbor, Michigan 48109-1055, United States.
J Am Chem Soc. 2015 Oct 14;137(40):12808-14. doi: 10.1021/jacs.5b08406. Epub 2015 Oct 1.
A new bifunctional pincer ligand framework bearing pendent proton-responsive hydroxyl groups was prepared and metalated with Ru(II) and subsequently isolated in four discrete protonation states. Stoichiometric reactions with H2 and HBPin showed facile E-H (E = H or BPin) activation across a Ru(II)-O bond, providing access to unusual Ru-H species with strong interactions with neighboring proton and boron atoms. These complexes were found to promote the catalytic hydroboration of ketones and nitriles under mild conditions, and the activity was highly dependent on the ligand's protonation state. Mechanistic experiments revealed a crucial role of the pendent hydroxyl groups for catalytic activity.
一种新的双功能钳形配体骨架带有悬垂质子响应性羟基，用 Ru(II) 进行金属化，并随后分离为四个离散的质子化态。与 H2 和 HBPin 的计量反应在 Ru(II)-O 键上易于进行 E-H（E = H 或 BPin）激活，提供了与相邻质子和硼原子具有强相互作用的不寻常的 Ru-H 物种。这些配合物被发现可以在温和条件下促进酮和腈的催化加氢硼化，活性高度依赖于配体的质子化态。机理实验揭示了悬垂羟基对催化活性的关键作用。
