Carbene transfer reactions between transition-metal ions

Carbene transfer processes are often involved in catalytic or metal-mediated reactions, however, a limited number of works concerning such transfer between transition metal complexes appear in the literature. This article presents an overview of the progress of this chemistry with an emphasis on examples with well-defined structures. A few studies, which are discussed in some detail, provide an insight of what has been achieved as well as an indication of the future work.