“(Diphosphine)Nickel”‐Catalyzed Negishi Cross‐Coupling: An Experimental and Theoretical Study

Abstract

The use of a strongly donating "(bis-dialkylphosphine)Ni" fragment promotes the catalytic coupling of a large range of ArCl and ArZnCl derivatives under mild conditions. Stoichiometric mechanistic investigations and DFT calculations prove that a Ni(0) /Ni(II) cycle is operative in this system.

Nickel‐Catalyzed Methylation of Aryl Halides with Deuterated Methyl Iodide

“…It is important to note that previous mechanistic studies by the groups of Fu, Vicic, Weix, and others, all suggest a Ni I /Ni III catalytic cycle is involved in such transformations. However, we found that a nickel‐catalyzed cross‐coupling between aryl electrophiles and alkyl electrophiles could also favor a Ni 0 /Ni II catalytic cycle …”

Reactions of nickel(0) with organochlorides, organobromides, and organoiodides: mechanisms and structure/reactivity relationships

“…31 Nicolas et al examined the oxidative addition of chloroarenes to [Ni(η 2 -C 6 H 5 Me)(dcpp)], in the context of nickel-catalysed Negishi cross-coupling reactions, using experimental and computational methodology (dcpp = 1,3-bis(dicyclohexylphosphino)propane). 32 [NiCl(Ar)(dcpp)] complexes were observed experimentally. Oxidative addition via a concerted transition state was found to have a rather low activation energy (ΔG ‡ = 12.9 kcal mol −1 ), with either transmetalation or the exchange of biaryl for chloroarene found to be the most energetically-demanding step.…”

Halide Abstraction Competes with Oxidative Addition in the Reactions of Aryl Halides with [Ni(PMenPh(3−n))4]

“…This mechanism differs from that established for [Pd(PPh 3 ) 4 ], which proceeds via [Pd(PPh 3 ) 2 ] and a concerted three‐centre transition state 17. Concerted three‐centre transition states have been computationally characterised for oxidative addition to Ni 0 complexes bearing bidentate phosphine ligands 9, 12, 14, 18, 19, 20. We present evidence from computational studies that Ni I and Ni II products both do indeed arise via [Ni(PEt 3 ) 3 ]; Ni I is obtained via an open‐shell singlet transition state and Ni II is formed from an S N 2‐type oxidative addition event (Figure 1 (b)).…”