Zirconocenes (zirconium (II) bis(alkylcyclopentadienyls)) “Zr (h5-C5H4R)” are very reactive species, having only 14 valence electrons.
The can be synthesized by reductive elimination:
(h5-C5H4R)Zr(H)(nBu) → (h5-C5H4R)Zr + HnBu
(h5-C5H4R)Zr(H)(Tol) → (h5-C5H4R)Zr + HTol (Tol = Tolyl)
Zirconocenes are potentially applicable as MOCVD precursors, however, their thermal decomposition leads to carbon contaminated films.