Cyclopentyne is a

cycloalkyne In organic chemistry, a cycloalkyne is the cyclic analog of an alkyne (). A cycloalkyne consists of a closed ring of carbon atoms containing one or more triple bonds. Cycloalkynes have a general formula Because of the linear nature of the alkyn ...

containing 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 mak ...

atoms in the ring. Due to the ideal

bond angle Bond or bonds may refer to: Common meanings * Bond (finance), a type of debt security * Bail bond, a commercial third-party guarantor of surety bonds in the United States * Chemical bond, the attraction of atoms, ions or molecules to form chemical ...

of 180° at each atom of the alkyne but the structural requirement that the bonds form a ring, this chemical is a highly strained structure, and the triple bond is highly reactive. The triple bond easily undergoes both +2and +2

cycloaddition In organic chemistry, a cycloaddition is a chemical reaction in which "two or more unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity". T ...

reactions. Unlike benzyne, which undergoes a +2addition with loss of stereochemistry at the alkene partner, cyclopentyne reacts with alkenes with retention of geometry of the partner, an example of the relevance of

orbital symmetry Molecular symmetry in chemistry describes the symmetry present in molecules and the classification of these molecules according to their symmetry. Molecular symmetry is a fundamental concept in chemistry, as it can be used to predict or explain m ...

even for highly reactive structures. The structure can also form a π complex with

lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid ...

cations, which affects the cycloaddition reactivity. It can even interact strongly enough with

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

species to form a novel type of

metallacycle In organometallic chemistry, a metallacycle is a derivative of a carbocyclic compound wherein a metal has replaced at least one carbon center; this is to some extent similar to heterocycles. Metallacycles appear frequently as reactive intermediates ...

References

{{reflist Reactive intermediates Alkynes Five-membered rings Hydrocarbons