Results and perspectives in the chemistry of side-chain-functionalized cyclopentadienyl compounds

Cyclopentadienyl (Cp) compounds of s-, p-, d-, and f-block elements with donor functionalities in the side-chain of the Cp fragment have attracted a lot of attention during the last decade. In this article, the structure and reactivity of representative compounds with tethered NR2, OR, PR2, SR, and CHCHR groups are described; one, two (in 1,3 position) or five donors are attached with Cn or SiCn spacers to the Cp fragment. Intra- or intermolecular donor—acceptor interactions can be classified with the help of the HSAB concept. A ‘hard—soft’ coordination promotes hemilability and causes interesting effects concerning reactivity. Side-chain-functionalized compounds find application in catalysis, CVD and related techniques, molecular recognition, organometallic chemistry in water, and dendrimer synthesis. Perspectives in these fields are presented.