Theoretical Studies of Metallabenzenes: From Bonding Situation to Reactivity

Metallabenzenes are characterized by the formal replacement of a CH unit in benzene by an isolobal transition-metal fragment. This chapter summarizes the insight gained into the chemistry of metallabenzenes from a computational point of view. It also covers issues such as the bonding situation, aromatic character, synthetic pathways and reactivity by describing the main works reported since the initial prediction by Thorn and Hoffmann. The molecular orbitals of metallabenzenes and particularly their frontier MO's have been discussed in numerous computational studies, where the emphasis was on the factors leading to the observed C-C bond length equalization. Various aromaticity descriptors have been computationally applied to diagnose the aromatic nature of metallabenzenes. The chapter summarizes the most relevant descriptors. It becomes evident that the study of metallabenzenes by means of computational methods has been key to understand and rationalize both the bonding situation and rich reactivity of this interesting family of organometallic compounds.