Cycloocta-1,5-diene is a

cyclic Cycle, cycles, or cyclic may refer to: Anthropology and social sciences * Cyclic history, a theory of history * Cyclical theory, a theory of American political history associated with Arthur Schlesinger, Sr. * Social cycle, various cycles in so ...

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...

with the chemical formula , specifically . There are three configurational isomers with this structure, that differ by the arrangement of the four C–C single bonds adjacent to the double bonds. Each pair of single bonds can be on the same side () or on opposite sides () of the double bond's plane; the three possibilities are denoted , , and ; or (), (), and (). (Because of overall symmetry, is the same configuration as .) Generally abbreviated COD, the isomer of this

diene In organic chemistry a diene ( ) (diolefin ( ) or alkadiene) is a covalent compound that contains two double bonds, usually among carbon atoms. They thus contain two alk''ene'' units, with the standard prefix ''di'' of systematic nomenclature. ...

is a useful precursor to other organic compounds and serves as a

ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elect ...

organometallic chemistry 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 s ...

. It is a colorless liquid with a strong odor. 1,5-Cyclooctadiene can be prepared by dimerization of

butadiene 1,3-Butadiene () is the organic compound with the formula (CH2=CH)2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two v ...

in the presence of a nickel catalyst, a coproduct being vinylcyclohexene. Approximately 10,000 tons were produced in 2005.

Organic reactions

COD reacts with borane to give 9-borabicyclo .3.1onane, commonly known as 9-BBN, a

reagent In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...

in organic chemistry used in

hydroboration In organic chemistry, hydroboration refers to the addition of a hydrogen-boron bond to certain double and triple bonds involving carbon (, , , and ). This chemical reaction is useful in the organic synthesis of organic compounds. Hydroboration p ...

s: :

COD adds (or similar reagents) to give 2,6-dichloro-9-thiabicyclo .3.1onane: : CODSCl2

The resulting dichloride can be further modified as the di

azide In chemistry, azide is a linear, polyatomic anion with the formula and structure . It is the conjugate base of hydrazoic acid . Organic azides are organic compounds with the formula , containing the azide functional group. The dominant appli ...

or di cyano derivative in a

nucleophilic substitution In chemistry, a nucleophilic substitution is a class of chemical reactions in which an electron-rich chemical species (known as a nucleophile) replaces a functional group within another electron-deficient molecule (known as the electrophile). The ...

aided by

anchimeric assistance In organic chemistry, neighbouring group participation (NGP, also known as anchimeric assistance) has been defined by the International Union of Pure and Applied Chemistry (IUPAC) as the interaction of a reaction centre with a lone pair of elec ...

Metal complexes

File:Ni(cod)2.png,

Bis(cyclooctadiene)nickel(0) Bis(cyclooctadiene)nickel(0) is the organonickel compound with the formula Ni(C8H12)2, also written Ni(cod)2. It is a diamagnetic coordination complex featuring tetrahedral nickel(0) bound to the alkene groups in two 1,5-cyclooctadiene ligands. Thi ...

. File: Crabtree.svg, Crabtree's catalyst. File: Cyclooctadiene-rhodium-chloride-dimer-2D-skeletal.png, The complex . File:Co(C8H12)(C8H13).png, Co(1,5-cyclooctadiene)(cyclooctenyl). File:PdCl2(cod).png, Dichloro(1,5‐cyclooctadiene)palladium File:Ir2Cl2 cod 2improved.svg,

cyclooctadiene iridium chloride dimer Cyclooctadiene iridium chloride dimer is an organoiridium compound with the formula r(μ2-Cl)(COD)sub>2, where COD is the diene 1,5-cyclooctadiene (C8H12). It is an orange-red solid that is soluble in organic solvents. The complex is used as a p ...

File:Cl2Ptcod.png, Dichloro(1,5‐cyclooctadiene)platinum 1,5-COD binds to low-valent metals via both alkene groups. Metal-COD complexes are attractive because they are sufficiently stable to be isolated, often being more robust than related ethylene complexes. The stability of COD complexes is attributable to the

chelate effect Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are ...

. The COD ligands are easily displaced by other ligands, such as phosphines. is prepared by reduction of

anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achi ...

nickel

acetylacetonate Acetylacetone is an organic compound with the chemical formula . It is a colorless liquid, classified as a 1,3-diketone. It exists in equilibrium with a tautomer . These tautomers interconvert so rapidly under most conditions that they are tre ...

in the presence of the ligand, using

triethylaluminium Triethylaluminium is one of the simplest examples of an organoaluminium compound. Despite its name it has the formula Al2( C2H5)6 (abbreviated as Al2Et6 or TEA), as it exists as a dimer. This colorless liquid is pyrophoric. It is an industrially ...

: The related is prepared by a more circuitous route involving the dilithium

cyclooctatetraene 1,3,5,7-Cyclooctatetraene (COT) is an unsaturated derivative of cyclooctane, with the formula C8H8. It is also known as nnulene. This polyunsaturated hydrocarbon is a colorless to light yellow flammable liquid at room temperature. Because of ...

: : : Extensive work has been reported on complexes of COD, much of which has been described in volumes 25, 26, and 28 of ''

Inorganic Syntheses ''Inorganic Syntheses'' is a book series which aims to publish "detailed and foolproof" procedures for the synthesis of inorganic compounds.cyclooctadiene rhodium chloride dimer Cyclooctadiene rhodium chloride dimer is the organorhodium compound with the formula Rh2Cl2(C8H12)2, commonly abbreviated hCl(COD)sub>2 or Rh2Cl2(COD)2. This yellow-orange, air-stable compound is a widely used precursor to homogeneous catalyst ...

, and , and Crabtree's catalyst. The complexes with nickel, palladium, and platinum have tetrahedral geometry, whereas complexes of rhodium and iridium are

square planar The square planar molecular geometry in chemistry describes the stereochemistry (spatial arrangement of atoms) that is adopted by certain chemical compounds. As the name suggests, molecules of this geometry have their atoms positioned at the corne ...

(''E'',''E'')-COD

The highly strained ''trans'',''trans'' isomer of 1,5-cyclooctadiene is a known compound. (''E'',''E'')-COD was first synthesized by

George M. Whitesides George McClelland Whitesides (born August 3, 1939) is an American chemist and professor of chemistry at Harvard University. He is best known for his work in the areas of nuclear magnetic resonance spectroscopy, organometallic chemistry, molecula ...

and Arthur C. Cope in 1969 by

photoisomerization In chemistry, photoisomerization is a form of isomerization induced by photoexcitation. Both reversible and irreversible photoisomerizations are known for photoswitchable compounds. The term "photoisomerization" usually, however, refers to a re ...

of the ''cis'',''cis'' compound. Another synthesis (double elimination reaction from a cyclooctane ring) was reported by

Rolf Huisgen Rolf Huisgen (; 13 June 1920 – 26 March 2020) was a German chemist. His importance in synthetic organic chemistry extends to the enormous influence he had in post-war chemistry departments in Germany and Austria, due to a large number of his ...

in 1987. The

molecular conformation A chemical structure determination includes a chemist's specifying the molecular geometry and, when feasible and necessary, the electronic structure of the target molecule or other solid. Molecular geometry refers to the spatial arrangement of a ...

of (''E'',''E'')-COD is twisted rather than chair-like. The compound has been investigated as a

click chemistry In chemical synthesis, click chemistry is a class of biocompatible small molecule reactions commonly used in bioconjugation, allowing the joining of substrates of choice with specific biomolecules. Click chemistry is not a single specific reactio ...

mediator.

References

{{DEFAULTSORT:Cyclooctadiene, 1, 5- Cycloalkenes Dienes Ligands Eight-membered rings Foul-smelling chemicals