Tridentate NacNac Tames T‐Shaped Nickel(I) Radical

The reaction of a nickel(II) chloride complex containing a tridentate β‐diketiminato ligand with a picolyl group [2,6‐iPr2‐C6H3NC(Me)CHC(Me)NH(CH2py)]Ni(II)Cl (1)] with KSi(SiMe3)3 conveniently afforded a nickel(I) radical with a T‐shaped geometry (2). The compound‘s metalloradical nature was confirmed through electron paramagnetic resonance (EPR) studies and its reaction with TEMPO, resulting in the formation of a highly unusual three‐membered nickeloxaziridine complex (3). When reacted with disulfide and diselenide, the S−S and Se−Se bonds were cleaved, and a coupled product was formed through carbon atom of the pyridine‐imine group. The nickel(I) radical activates dihydrogen at room temperature and atmospheric pressure to give the monomeric nickel hydride. A thermally stable, T‐shaped, nickel(I) radical was straightforward obtained by reduction of a tridentate nacnac nickel(II) chloride with KSi(TMS)3. The metalloradical character of the compound was demonstrated by the formation of a highly unusual nickeloxaziridine complex upon addition of TEMPO. The Ni(I) species displays a rich chemistry towards activation S−S, and Se−Se bond leading to unusual C−C coupled product as well as dihydrogen activation at room temperature and atmospheric pressure to generate monomeric nickel hydride.