Mechanistic insight into carbon–fluorine cleavage with a ( Pr3P)2Ni source: Characterization of ( Pr3P)2NiC6F5 as a significant Ni(I) byproduct in the activation of C6F6
作者:Jillian A. Hatnean、Manar Shoshani、Samuel A. Johnson
DOI:10.1016/j.ica.2014.07.023
日期:2014.10
The reaction of ((Pr3P)-Pr-i)(2)Ni sources such as the anthracene adduct, ((Pr3P)-Pr-i)(2)Ni(eta(2)-C14H10), with hexafluorobenzene provided the C-F activation product trans-((Pr3P)-Pr-i)(2)NiF(C6F5) (2) and the unexpected Ni(I) complex ((Pr3P)-Pr-i)(2)Ni(C6F5) (3). The observation of 3 supports a radical pathway for C-F activation, despite the observation of the mononuclear adduct ((Pr3P)-Pr-i)(2)Ni(eta(2)-C6F6) (4) commonly associated with concerted or phosphine-assisted oxidative addition. Carbon-fluorine activation reactions of pentafluorobenzene and all the isomers of tetrafluorobenzene and trifluorobenzene with ((Pr3P)-Pr-i)(2)Ni(eta(2)-C14H10) were also examined. These reacted with varying selectivity and yield. It was found that 1,2,3,4-tetrafluorobenzene reacted selectively at the 2-position to provide a fully characterized C-F activation product, whereas 1,2,4,5-tetrafluorobenzene underwent a hydrodefluorination reaction with none of the expected C-F activation product. (C) 2014 Elsevier B. V. All rights reserved.