A rotane is a hydrocarbon consisting of a central cycloalkane ring with cyclopropane units spiro-linked to each corner. The systematic naming pattern for these molecules is 'rotane', where n is the number of atoms in the central ring. A rotane is a hydrocarbon consisting of a central cycloalkane ring with cyclopropane units spiro-linked to each corner. The systematic naming pattern for these molecules is 'rotane', where n is the number of atoms in the central ring. The simplest such chemical, rotane, consists solely of a branched array of spiro-cyclopropane units, and is thus a branched triangulane.