Synthesis, structure and electrochemical properties of the organonickel complex [NiBr(Mes)(phen)] (Mes = 2,4,6-trimethylphenyl, phen = 1,10-phenanthroline)

The organonickel complex [NiBr(Mes)(phen)] (1) (Mes = 2,4,6-trimethylphenyl, phen = 1,10-phenanthroline) was synthesized by oxidative addition of MesBr to nickel(0) complexes, obtained from [Ni(COD)2] (COD = 1,5-cyclooctadiene) and phen, or electrochemically generated from [NiBr2(phen)], and by ligand exchange reaction from [NiBr(Mes)(PPh3)2]. The electrochemical properties of [NiBr(Mes)(phen)] were investigated by cyclic voltammetry and in situ EPR spectroelectrochemistry. The cathodic reduction of 1 resulted in formation of the neutral radical complex [Ni(Mes)(phenradical dot−)] with a 1,10-phenanthroline radical anion bound to a nickel(II) centre. The electrochemical generation of the free 1,10-phenanthroline radical anion from 1,10-phenanthroline is also described.