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![]() "Herringbone" crystal structure of [18]annulene
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Names | |||
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Preferred IUPAC name
(1Z,3E,5E,7Z,9E,11E,13Z,15E,17E)-Cyclooctadeca-1,3,5,7,9,11,13,15,17-nonaene | |||
Identifiers | |||
3D model (JSmol)
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ChemSpider | |||
PubChem CID
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Properties | |||
C18H18 | |||
Molar mass | 234.3 g·mol−1 | ||
Appearance | red-brown crystals | ||
Density | 1.134 g/cm3 (calc.)[1] | ||
Structure[1] | |||
monoclinic, P21/a | |||
a = 1.4984 (5) nm, b = 0.4802(2) nm, c = 1.0260(3) nm α = 90°, β = 111.52(1)°, γ = 90°
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Formula units (Z)
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2 | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Cyclooctadecanonaene or [18]annulene is an organic compound with chemical formula C
18H
18. It belongs to the class of highly conjugated compounds known as annulenes and is aromatic. The usual isomer that [18]annulene refers to is the most stable one, containing six interior hydrogens and twelve exterior ones, with the nine formal double bonds in the cis,trans,trans,cis,trans,trans,cis,trans,trans configuration. It is reported to be a red-brown crystalline solid.