triangulane

File:Spiro(2.2)pentane skeletal.svg-linked cyclopropane rings]]

A triangulane is a hydrocarbon consisting exclusively of a series of spiro-linked cyclopropane rings.{{cite journal |first1= Nikolai S. |last1= Zefirov |first2= Serge I. |last2= Kozhushkov |first3= T. S. |last3= Kuznetsova |first4= O. V. |last4= Kokoreva |first5= K. A. |last5= Lukin |first6= B. I. |last6= Ugrak |first7= Serge S. |last7= Tratch |journal= J. Am. Chem. Soc. |year= 1990 |volume= 112 |issue= 21 |pages= 7702–7707 |title= Triangulanes: stereoisomerism and general method of synthesis |doi= 10.1021/ja00177a034 }}

Triangulanes are named according to the rules of systematic nomenclature for spiro compounds.{{Cite journal |last=Moss |first=G. P. |date=1999-03-30 |title=Extension and revision of the nomenclature for spiro compounds |url=https://www.degruyter.com/document/doi/10.1351/pac199971030531/html |journal=Pure and Applied Chemistry |language=en |volume=71 |issue=3 |pages=531–558 |doi=10.1351/pac199971030531 |issn=1365-3075|doi-access=free }} The pattern of their common names is "[n]triangulane", where n is the number of cyclopropane units. The simplest such chemical, [2]triangulane, is named spiro[2.2]pentane by systematic nomenclature. Chains consisting of four or more cyclopropane units—[4]triangulane and higher—can form chiral helices. This property is unusual for a molecule that contains no stereogenic atoms; the chiral nature is due to restricted mobility of the chain ends analogous to helicene molecules.

The rings can form a branched or cyclic patterns. For example, [3]rotane is a branched [4]triangulane; it consists of one additional cyclopropane attached to the central ring of a [3]triangulane chain.{{cite journal |journal= Pure Appl. Chem. |volume= 75 |issue= 5 | pages= 549–562 |year= 2003 |title= New structurally interesting cyclopropane derivatives. A world of wonders and surprises |first1= Armin |last1= de Meijere |first2= Sergei I. |last2= Kozhushkov |first3= Andrey A. |last3= Fokin |first4= Ingo |last4= Emme |first5= Stefan |last5= Redlich |first6= Peter R. |last6= Schreiner |doi= 10.1351/pac200375050549 |s2cid= 15320567 |url= https://www.iupac.org/publications/pac/2003/pdf/7505x0549.pdf }}