Metallacycloalkanes – Synthesis, Structure and Reactivity of Medium to Large Ring Compounds

Publisher Summary This chapter discusses metallacyclopentane and larger rings containing only one transition metal. It focuses on the synthesis, structure, reactivity, and applications of metallacycles. The preparation of saturated five-membered metallacycles containing a group 4 transition metal has been extensively investigated and a number of synthetic routes are available for complexes of this type. Reactions of metallocene dichlorides with 1,4-dilithiobutane or the corresponding di-Grignard reagent represent the most common methods for preparation of these compounds. Although there are no reports of metallacyclohexane compounds for groups 5 or 6, there is a report of a group 7 rhenacyclohexane compound. The few reports can possibly be attributed to the fact that most of the routes to the metallacycles of this type make use of ethylene co-ordination, followed by coupling. There are no reported metallacycloheptane compounds of group 4 or group 5 transition metals. There is, however, a report of a chromacycloheptane 107.There are no reported metallacycloalkanes higher than metallacycloheptanes reported for the groups 4–7 and 9 transition metals.