Cyclopentadienyl magnesium bromide is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one ele ...

with the

molecular formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

. The molecule consists of a

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...

atom bonded to a

bromine Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table (halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simil ...

atom and a

cyclopentadienyl Cyclopentadienyl can refer to * Cyclopentadienyl anion, or cyclopentadienide, **Cyclopentadienyl ligand A cyclopentadienyl complex is a coordination complex of a metal and cyclopentadienyl anion, cyclopentadienyl groups (, abbreviated as Cp−) ...

group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic ide ...

, a ring of five

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes ...

s each with one

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

atom. The compound is a Grignard reagent, a type of

organometallic compound Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...

that features a magnesium atom bonded to a halogen atom and to a carbon atom of some organic

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the res ...

. This compound is of historic importance as the starting material for the first published synthesis of

ferrocene Ferrocene is an organometallic compound with the formula . The molecule is a complex consisting of two cyclopentadienyl rings bound to a central iron atom. It is an orange solid with a camphor-like odor, that sublimes above room temperature, ...

Peter Pauson Prof Peter Ludwig Israel Pauson FRSE FRIC (1925–2013) was a German–Jewish emigrant who settled in Britain and who is remembered for his contributions to chemistry, most notably the Pauson–Khand reaction and as joint discoverer of ferrocene. ...

and

Thomas J. Kealy Thomas Joseph Kealy (December 22, 1927 – May 17, 2012) was an American chemist. Personal He was born in 1927 to Thomas S. Kealy (from Ireland) and Josephine Kealy (born Frawley), in New York. He had three siblings, including John F. and Josephine ...

in 1951.

Preparation

The compound can be prepared by reacting

cyclopentadiene Cyclopentadiene is an organic compound with the formula C5H6.LeRoy H. Scharpen and Victor W. Laurie (1965): "Structure of cyclopentadiene". ''The Journal of Chemical Physics'', volume 43, issue 8, pages 2765-2766. It is often abbreviated CpH beca ...

with magnesium and

bromoethane Bromoethane, also known as ethyl bromide, is a chemical compound of the haloalkanes group. It is abbreviated by chemists as EtBr (which is also used as an abbreviation for ethidium bromide). This volatile compound has an ether-like odor. Prepara ...

in anhydrous

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen ato ...

References

P. L. Pauson and T. J. Kealy (1951): "A New Type of Organo-Iron Compound". ''Nature'', volume 168, issue 4285, pages 1039–1040. H. Werner (2012): "At Least 60 Years of Ferrocene: The Discovery and Rediscovery of the Sandwich Complexes". ''Angewandte Chemie International Edition'', volume 51, issue 25, pages 6052–6058. {{chem-stub Magnesium compounds Bromides Cyclopentadienyl complexes