Electrochemical synthesis of organonickel sigma-complexes

The electrochemical reduction of [NiBr2(bpy)] (bpy is 2,2'-bipyridine) complex in the presence of aryl bromide in undivided electrochemical cell supplied with a sacrificial nickel anode results in the one-pot formation of an organonickel complex [NiBr(aryl)(bpy)]. 


The oxidative addition of mesityl bromide either to electrochemically generated [Ni(bpy)] or to [Ni(COD)2] (COD = 1,5-cyclooctadiene) in the presence of 2,2'-bipyridine allows the selective, high-yield synthesis of the r-aryl complex [NiBr(Mes)(bpy)] (Mes = 2,4,6-trimethylphenyl, bpy = 2,2'-bipyridine), which is an efficient catalyst precursor for the oligomerization of ethylene to even-numbered olefins in the C4–C26 range with a Schulz–Flory distribution.