β-Protic pyrazole and N-heterocyclic carbene complexes: synthesis, properties, and metal-ligand cooperative bifunctional catalysis.

This Minireview provides an overview of the chemistry of pyrazole and N-heterocyclic carbene (NHC) complexes bearing an NH group at the β-position to the metal. The synthesis and structures as well as the Brønsted acidic nature of the β-NH group are described in detail. These complexes are attractive candidates for novel metal-ligand cooperative bifunctional catalysts, which would benefit highly effective molecular and energy transformations.