Chemistry of Metallabenzynes and Rhenabenzenes

This chapter first aims to summarize authors' work in the development of chemistry of rhenabenzenes, metallabenzenes containing a group 7 metal. It also aims to summarize their progress in the development of the chemistry of metallabenzynes. The original route to make metallabenzynes involves the reactions of the osmium complex OsCl2(PPh3)3 with alkynes. Nucleophiles can add to metallabenzynes. The reactivity and regioselectivity of these reactions are dependent on the ligands as well as the substituents on the metallacycle. Rearrangement of metallabenzenes to cyclopentadienyl complexes is one of the common reactivities of metallabenzenes. A series of metallabenzynes with Os or Re are isolated. These metallacycles can be regarded as aromatic compounds based on the criteria of electronic structure, geometry, reactivity, aromatic stabilization energy (ASE), and magnetic properties. They show reactivity of both aromatic systems (e.g. they can undergo electrophilic substitution reaction) and organometallic compounds (e.g. they can undergo migratory insertion reactions to form carbene complexes).