Weblinks https://en.wikipedia.org/wiki/Metallocene https://en.wikipedia.org/wiki/Cyclopentadienyl_complex
Suggested readings Organic synthesis: The disconnection approach Second edition by Stuart Warren, Paul Wyatt
Organic synthesis by Jagdamba Singh and LD.S. Yadav CHEMISTRY Paper No. 14: Organic Chemistry- IV (Advanced Organic Synthesis, supramolecular chemistry and carbocyclic rings) Module No. 31: Metallocenes
CHEMISTRY Paper No. 14: Organic Chemistry- IV (Advanced Organic Synthesis, supramolecular chemistry and carbocyclic rings) Module No. 31: Metallocenes
Organic synthesis concepts and method by E.J. Corey
Glossary
B
Bent metallocenes: In bent metallocenes, the ring systems coordinated to the metal are not parallel, but are tilted at an angle.
C
Comproportionation: Comproportionation or symproportionation is a chemical reaction where two reactants, each containing the same element but with a different oxidation number, will form a product in which the elements involved reach the same oxidation number.
D
Decomposition: Decomposition is the process by which organic substances are broken down into a much simpler form of matter.
Dimer: A dimer is an oligomer consisting of two structurally similar monomers joined by bonds that can be either strong or weak, covalent or intermolecular.
Disproportionation: Disproportionation is a specific type of redox reaction in which a species is simultaneously reduced and oxidised to form two different products.
F
CHEMISTRY Paper No. 14: Organic Chemistry- IV (Advanced Organic Synthesis, supramolecular chemistry and carbocyclic rings) Module No. 31: Metallocenes
Ferrocene: Ferrocene is an organometallic compound with the formula Fe(C₅H₅)₂. It is the prototypical metallocene, a type of organometallic chemical compound consisting of two cyclopentadienyl rings bound on opposite sides of a central metal atom.
H
Half sandwich compounds: Half sandwich compounds are organometallic complexes that feature a cyclic polyhapto ligand bound to an MLn center, where L is a unidentate ligand. Thousands of such complexes are known.
Hapticity: Hapticity is the coordination of a ligand to a metal center via an uninterrupted and contiguous series of atoms. The hapticity of a ligand is described with the Greek letter η ('eta').
L
Ligands: Ligands are ions or neutral molecules that bond to a central metal atom or ion. Ligands act as Lewis bases (electron pair donors), and the central atom acts as a Lewis acid (electron pair acceptor). Ligands have at least one donor atom with an electron pair used to form covalent bonds with the central atom.
M
Metallocene: A metallocene is a compound typically consisting of two cyclopentadienyl anions bound to a metal center in the oxidation state II, with the resulting general formula (C₅H₅)₂M.
S
Salt metathesis reaction: A salt metathesis reaction sometimes called a double replacement reaction or double displacement reaction, is a chemical process involving the exchange of bonds between two reacting chemical species, which results in the creation of products with similar or identical bonding affiliations
Sandwich compound: In organometallic chemistry, a sandwich compound is a chemical compound featuring a metal bound by haptic covalent bonds to two arene ligands.
T
Transition elements: The transition elements are those elements having a partially filled d or f subshell in any common oxidation state.
Value addition
CHEMISTRY Paper No. 14: Organic Chemistry- IV (Advanced Organic Synthesis, supramolecular chemistry and carbocyclic rings) Module No. 31: Metallocenes
History of Meallocene
The first metallocene to be classified was ferrocene, and was discovered simultaneously in 1951 by Keally and Pauson, and Miller et al. Keally and Pauson were attempting to synthesize fulvalene through the oxidation of a cyclopentadienyl salt with anhydrous FeCl3 but obtained instead the substance C10H10Fe At the same time, Miller et al reported the same iron product from a reaction of cyclopentadiene with iron in the presence of aluminum, potassium, or molybdenum oxides. The structure of "C10H10Fe" was determined by Wilkinson et al. and by Fischer et al. These two were awarded the Nobel Prize in Chemistry in 1973 for their work on sandwich compounds, including the structural determination of ferrocene. They determined that the carbon atoms of the cyclopentadienyl (Cp) ligand contributed equally to the bonding and that bonding occurred due to the metal d-orbitals and the π-electrons in the p-orbitals of the Cp ligands. This complex is now known as ferrocene and the group of transition metal dicyclopentadienyl compounds is known as metallocenes and have the general formula [(η5- C5H5)2M]. Fischer et al. first prepared the ferrocene derivatives involving Co and Ni. Often derived from substituted derivatives of cyclopentadienide, metallocenes of many elements have been prepared.
CHEMISTRY Paper No. 14: Organic Chemistry- IV (Advanced Organic Synthesis, supramolecular chemistry and carbocyclic rings) Module No. 31: Metallocenes