Synthesis and Reactivity of Paramagnetic Nickel Polypyridyl Complexes Relevant to C(sp ² )–C(sp ³ )Coupling Reactions

A number of new transition metal catalyzed methods for the formation of C(sp ² )–C(sp ³ ) bonds have recently been described. These reactions often utilize bidentate polypyridyl-ligated Ni catalysts, and paramagnetic Ni ^I halide or aryl species are proposed in the catalytic cycles. However, there is little knowledge about complexes of this type. Here, we report the synthesis of paramagnetic bidentate polypyridyl-ligated Ni halide and aryl complexes through elementary reactions proposed in catalytic cycles for C(sp ² )–C(sp ³ ) bond formation. We investigate the ability of these complexes to undergo organometallic reactions that are relevant to C(sp ² )–C(sp ³ ) coupling through stoichiometric studies and also explore their catalytic activity.