Ligand effects on the properties of Ni(iii) complexes: aerobically-induced aromatic cyanation at room temperature.

A series of organometallic Ni and Ni complexes supported by tertadendate N3C ligands were synthesized and fully characterized using X-ray crystallography, CV, and EPR. Based on the solid state structures, the substituents on the two amine N-donors significantly affect the coordination of the Ni centers, while the para substituents of the phenyl C-donor have a reduced effect. This is further supported by electrochemical and spectroscopic measurements that suggest the presence of a less bulky N-substituent of the N3C ligand leads to a more accessible Ni center. These results also suggest that the (N3C)Ni system should be more reactive toward oxidation than the corresponding (N3C)Ni and (N3C)Ni systems. Indeed, aerobic oxidative aromatic cyanation was achieved with the (N3C)Ni system at room temperature.