In this work, a new dual photoredox nickel catalysis system has been utilized for the synthesize of aryl amines. Previously, our group has shown that a nickel catalyst in conjunction with a photosensitizer and a sacrificial electron donor can cross-couple C−C bonds via photoredox-assisted reductive coupling. Here we have built upon that system to develop a redox-neutral cross-coupling system for the formation of C−N bonds. The catalytic system is composed of just a nickel cross-coupling catalyst, a Ru photocatalyst, and base and is capable of coupling amines with aryl halides in good to excellent yields. Furthermore, it was found that these reactions are functional under ambient conditions with catalyst loadings of 1 mol %. Spectroscopic studies provide support that this amination mechanism proceeds via a nitrogen-based radical intermediate. This N-radical mechanism offers direct synthetic access to di-and triaryl amines from nickel photocatalysis.

A molecular/heterogeneous catalyst motif based on an earth abundant nickel catalyst and SiO 2 support has been designed and synthesized. Characterization and catalytic testing indicate that the molecular nickel catalyst [(2,2′:6′,2′′-terpyridine-4′-benzoic acid)Ni(II)]Cl 2 attached to a high surface area SiO 2 support is the active cross-coupling catalyst and increased product yields are a result of increased molecular stability of the catalyst while attached to the SiO 2 support. This molecular/heterogeneous motif is easily separated from reaction mixtures and can be recycled for multiple catalytic reactions. The catalyst is active for Suzuki− Miyaura catalysis at catalyst loadings as low as 0.1 mol %, and turnover numbers nearing 2000 have been achieved.

Atomic layer deposition immobilizes molecular catalysts on solid supports, which prevents molecular deactivation pathways and leads to longer catalyst lifetimes in high aqueous content solvents.