The cyclometalated nickel complex [(Phbpy)NiBr] (Phbpy− = 2,2′-bipyridine-6-phen-2-yl) – Synthesis, spectroscopic and electrochemical studies

•New organometallic nickel complexes [(Phbpy)NiBr] and [(Phbpy)Ni(CF3)].•Single crystal XRD and NMR reveal cyclometalation.•Reversible oxidations and reduction from cyclic voltammetry.•Partly reversible oxidations and reductions from spectroelectrochemistry.•Oxidatively induced C–C coupling yields 2-CF3-Phbpy from [(Phbpy)Ni(CF3)].

The new organometallic nickel complex [(Phbpy)NiBr] containing the anionic tridentate N,N,C ligand 6-(phen-2-yl)-2,2′-bipyridine (Phbpy−) was synthesised from PhbpyBr and [Ni(COD)2] in excellent yields and was fully characterised (MS, NMR, single crystal XRD). [(Phbpy)NiBr] was reacted with (CF3)SiMe3 giving the CF3 complex [(Phbpy)Ni(CF3)]. Both new complexes were studied in detail by electrochemical (CV) and spectroelectrochemical (UV/vis/NIR absorption) methods. For both complexes the first one-electron reduction and the first oxidation of the Br complex occur fully reversible in the CV, while spectroelectrochemistry shows decomposition reactions. The CF3 complex is unstable in solution producing 2-CF3-Phbpy. Reactivity patterns for these reactions were discussed, also in comparison with the non-cyclometalated complex [(bpy)Ni(Mes)Br].

Graphical abstractThe new cyclometalated nickel complex [(Phbpy)NiBr] (Phbpy = (phen-2-yl)-2,2′-bipyridine) was synthesised from PhbpyBr and [Ni(COD)2]. Reaction of [(Phbpy)NiBr] with (CF3)SiMe3 gave the complex [(Phbpy)Ni(CF3)]. Both were analysed (XRD, NMR, MS) and studied by electrochemical (CV) and spectroelectrochemical (UV/vis/NIR absorption) methods revealing redox-induced activation.Figure optionsDownload full-size imageDownload as PowerPoint slide