High-valent Ni coordination compounds

Since the publication of the second edition of Comprehensive Coordination Chemistry in 2003, significant progress has been made by numerous research groups around the world in isolating high-valent Ni(III) and Ni(IV) complexes. A majority of this progress has been specific to the field of organometallic nickel chemistry, due largely to the increasing role that high-valent nickel species were shown to play in carbon-carbon and carbon-heteroatom bond forming reactions. Within this chapter, we have attempted to thoroughly catalog both coordination and organometallic Ni(III) and Ni(IV) complexes that have been isolated since 2003. Furthermore, we have grouped complexes related to the general ligand frameworks used for their stabilization, along with providing brief synthetic routes to these high-valent complexes. Also discussed within this chapter are the key spectroscopic and physical characteristics of these complexes, which make them relevant for various research areas such as synthetic organometallic and bioinorganic chemistry. We hope that a comprehensive grouping of such complexes along with the spectroscopic and physical characteristics provided will aid researchers in taking rational approaches toward the synthesis of a wider range of high-valent nickel species, as well as deciphering their roles in various oxidative transformations such as CeH bond activation and functionalization reactions.