Ferrocene-zirconium complexes

Mori M (2005) Synthesis and Reactivity of Zirconium-Silene Complexes. 10 41-62 Moriuchi T, Hirao T (2006) Ferrocene-Peptide Bioconjugates. 17 143-175 Morokuma K, see Musaev G (2005) 12 1-30... 

Iminophosphoranes, mercuration, 2, 432 (Iminophosphoranyl)ferrocenes, synthesis, 6, 202 Imino-pyrrolate systems, with zirconium, 4, 1138-1139 Imino-pyrrolides, with Zr(IV) and Hf(IV), 4, 780 Imino-pyrrolyl ligands, in chromium complexes, 5, 355 Iminosilanes, reactions, 3, 440 Imprinted complexes, on oxide surface, 12, 810 Impurities, glovebox techniques, 1, 215 Inclusion chemistry... 

The titanium (or zirconium) present in these complexes is in an oxidation state of +4 and therefore has 0 valence electrons. Each Cp contributes 6e each, making a total of 12e. Each Cf contributes 2e each. Thus, Cp2ZrCl2 and Cp2TiCl2 are 16e compounds and therefore are more reactive than ferrocene. Further the bent structure of metallocenes allows additional ligands to approach the metal ion. 

The name of metallocenes is derived from ferrocene, which is a complex compound of iron with dicyclopentadiene. The metallocene complexes are new types of Ziegler-Natta catalysts. The general formula of these catalysts is identified as Cp MeCl, where Cp denotes the cyclopentadiene ring or its derivatives. Me is metal atom, which the most often is zirconium (Zr), hafhium (Hf), titanium (Ti), scandium (Sc), thorium (Th) or another rare earth element. 

Metallocene chemistry is presently a very promising field of inorganic chemistry. E.g., metallocene complexes of titanium and zirconium play an important role in the production of polymers. The role of ferrocene derivatives as effective nucleophilic catalysts in kinetic resolutions of many useful... 

Metallocenes have been used for complexes which have sandwich structures with two cyclopentadienyl ligands since the discovery of ferrocene. Recently metal complexes having one cyclopentadienyl ligand have also been classified as a member of metallocene derivatives. One important discovery in this area is the olefin polymerization catalyzed by metallocene complexes of early transition metals such as zirconium and titanium. In particular, the structure of the metallocene catalyst has a remarkable effect on the structure of the polymers. This discovery has had a strong impact on the industry. 

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