Aerobic oxidation-functionalization of the aryl moiety in van Koten's pincer complex (NCN)Ni(ii)Br: relevance to carbon–heteroatom coupling reactions promoted by high-valent nickel species

Abstract

The growing popularity of metal-promoted C-H functionalization methodologies has led to increased efforts aimed at improving our understanding of the mechanistic underpinnings of C-C or C-heteroatom bond forming steps. One...

Taming the Lewis Superacid Al(ORF)3 (RF=C(CF3)3): DFT Guided Identification of the “Stable yet Reactive” Adduct SiPr2→Al(ORF)3; Its Use as ORF‐ Abstractor from a “Ni‐ORF” complex

“…For example nickel-alkoxides are demonstrated to be intermediates in coupling processes (via ligand exchange or β-H abstraction, Scheme 3, top). [23,[41][42][43][44][45][46] Furthermore, insertion in NiÀ O bonds of CO 2 , CO, nitriles, ketones, isocyanate (Scheme 3, bottom); [35,36,38,39] has been established for neutral mono-alkoxide nickel complexes; as well as [OR] À ligand exchange [33] and formal reductive elimination at Ni. [37] During these studies, and as mentioned by Krossing et al, we observed that PhF!Al(OR F ) 3 adduct suffers from poor thermal stability liberating the Al(OR F ) 3 Lewis acid at room temperature, that evolves via abstraction of one of its own fluorine to form the [(R F O) 2 Al(μ-F)] 3 ring 2 (see below, Scheme 4).…”

“…Apart from these scattered examples, complexes featuring Ni−O bonds are quite reactive. For example nickel‐alkoxides are demonstrated to be intermediates in coupling processes (via ligand exchange or β‐H abstraction, Scheme 3, top) [23,41–46] . Furthermore, insertion in Ni−O bonds of CO 2 , CO, nitriles, ketones, isocyanate (Scheme 3, bottom); [35,36,38,39] has been established for neutral mono‐alkoxide nickel complexes; as well as [OR] − ligand exchange [33] and formal reductive elimination at Ni.…”