Arene CH Amination at Nickel in Terphenyl–Diphosphine Complexes with Labile Metal–Arene Interactions

The meta ‐terphenyl diphosphine, m ‐P 2 , 1 , was utilized to support Ni centers in the oxidation states 0, I, and II. A series of complexes bearing different substituents or ligands at Ni was prepared to investigate the dependence of metal–arene interactions on oxidation state and substitution at the metal center. Complex ( m ‐P 2 )Ni ( 2 ) shows strong Ni 0 –arene interactions involving the central arene ring of the terphenyl ligand both in solution and the solid state. These interactions are significantly less pronounced in Ni 0 complexes bearing L‐type ligands ( 2‐L : L=CH 3 CN, CO, Ph 2 CN 2 ), Ni I X complexes ( 3‐X : X=Cl, BF 4 , N 3 , N 3 B(C 6 F 5 ) 3 ), and [( m ‐P 2 )Ni II Cl 2 ] ( 4 ). Complex 2 reacts with substrates, such as diphenyldiazoalkane, sulfur ylides (Ph 2 SCH 2 ), organoazides (RN 3 : R= para ‐C 6 H 4 OMe, para ‐C 6 H 4 CF 3 , 1‐adamantyl), and N 2 O with the locus of observed reactivity dependent on the nature of the substrate. These reactions led to isolation of an η 1 ‐diphenyldiazoalkane adduct ( 2‐Ph 2 CN 2 ), methylidene insertion into a NiP bond followed by rearrangement of a nickel‐bound phosphorus ylide ( 5 ) to a benzylphosphine ( 6) , Staudinger oxidation of the phosphine arms, and metal‐mediated nitrene insertion into an arene CH bond of 1 , all derived from the same compound ( 2 ). Hydrogen‐atom abstraction from a Ni I –amide ( 9 ) and the resulting nitrene transfer supports the viability of Ni–imide intermediates in the reaction of 1 with 1‐azido‐arenes.