494199-72-3Relevant academic research and scientific papers
Planar-locked Ru-PNN catalysts in 1-phenylethanol dehydrogenation
Fanara, Paul M.,MacMillan, Samantha N.,Lacy, David C.
, p. 3628 - 3644 (2020/11/03)
Ru-PNN pincer catalysts of the general form [{PNN}Ru(H)(Cl)(CO)] can dehydrogenate alcohols through inner- and outer-sphere mechanisms, but determining the favored path is challenging. To address this challenge, the following planar-locked quinoline-based PNN ligands, which cannot form key inner-sphere transition states and intermediates, were synthesized: 2-((ditertbutylphosphaneyl)methyl)-N,N-diethylquinolin-8-amine (QNPtBu), 2-((diisopropylphosphaneyl)methyl)-N,N-diethyl-quinolin-8-amine (QNPiPr), and 2-((diphenylphosphaneyl)-methyl)-N,N-diethylquinolin-8-amine (QNPPh). In addition to the quinoline-derived ligands, we also prepared the isoquinoline PNN ligand N-((1-((ditert-butylphosphaneyl)methyl)isoquinolin-3-yl)methyl)-N-ethylethanamine (IsoQNP) and two known picoline- and lutidine-derived ligands 2-((ditert-butylphosphaneyl)-methyl)pyridine (PicP) and 2-((ditert-butylphosphaneyl)methyl)-6-methylpyridine (LutP). These six ligands were coordinated to Ru(II) ions to prepare six new complexes of the general formulation [{L}Ru(H)(Cl)(CO)] analogous to Milstein’s PNN catalyst precursor (1PyCl). The X-ray structural, NMR, UV-vis, and FTIR spectroscopic properties of the new complexes are similar to parent complex 1PyCl and were used in catalytic 1-phenylethanol acceptor-less and transfer dehydrogenation. The comparative results demonstrate that 1Py outperforms the other catalysts. DFT reaction profiles were computed for 1Py and the planar-locked catalysts. The results suggest that 1Py has access to a lower-energy inner-sphere path, whereas the planar-locked catalysts can only proceed through a high-energy outer-sphere mechanism and may even get trapped in unreactive alkoxide sinks.
Role of Phosphine Sterics in Strained Aminophosphine Chelate Formation
Bowes, Eric G.,Dawson Beattie,Love, Jennifer A.
supporting information, p. 2925 - 2929 (2019/03/02)
The preparation of four-membered aminophosphine (PN) chelates from common metal precursors has largely evaded realization because of the ring strain associated with these species. We report a straightforward approach to the synthesis of such PN metallacycles using simple α-PN ligands analogous to the popular class of small-bite-angle diphosphinomethane ligands. It is demonstrated that bulky phosphine substituents are important to the formation of these chelates.
Iron-catalyzed, atom-economical, chemo- and regioselective alkene hydroboration with pinacolborane
Zhang, Lei,Peng, Dongjie,Leng, Xuebing,Huang, Zheng
supporting information, p. 3676 - 3680 (2013/04/23)
Precious iron: A new PNN iron complex has been developed for use in an iron-catalyzed alkene hydroboration reaction under mild conditions. The environmentally friendly and earth-abundant iron catalyst system is superior to precious-metal systems in terms of efficiency and selectivity for α-olefin hydroborations with pinacolborane. Copyright
