Bent metallocenes revisited

The orbital structure of bent metallocenes and how their geometry depends on the number of d electrons are described. Bonding by a metallocene unit is exemplified by reference to the known hydrides. The reactivity of metallocene derivatives is illustrated with particular emphasis on the differences between ansa-bridged and unbridged compounds; the reactions include ring opening polymerisation of ferrocenophanes, elimination from and addition to Group 6 metallocene derivatives and Ziegler–Natta polymerisation of olefins by Group 4 metallocenes.