▁a ▁series ▁of ▁sp iro - link ed ▁cy clo prop ane ▁rings . ▁The ▁system atic ▁naming ▁pattern ▁for ▁these ▁mole cules ▁is ▁"[ n ] tri ang ul ane ", ▁where ▁n ▁is ▁the ▁number ▁of ▁cy clo prop ane ▁units . ▁ ▁The ▁simplest ▁such ▁chemical , ▁[ 2 ] tri ang ul ane ▁by ▁the ▁system atic ▁nom en cl ature ▁of ▁this ▁class , ▁is ▁named ▁sp iro [ 2 . 2 ] pent ane ▁by ▁standard ▁sp iro cyc lic ▁structure ▁nom en cl ature . ▁Ch ains ▁consisting ▁of ▁four ▁or ▁more ▁cy clo prop ane ▁units — [ 4 ] tri ang ul ane ▁and ▁higher — can ▁form ▁ch iral ▁hel ices . ▁This ▁property ▁is ▁unusual ▁for ▁a ▁mole c ule ▁that ▁contains ▁no ▁s tere ogen ic ▁atoms ; ▁the ▁ch iral ▁nature ▁is ▁due ▁to ▁restricted ▁mob ility ▁of ▁the ▁chain ▁ends ▁analog ous ▁to ▁hel ic ene ▁mole cules . ▁▁ ▁The ▁rings ▁can ▁form ▁a ▁branch ed ▁or ▁cy clic ▁patterns . ▁For ▁example , ▁[ 3 ] rot ane ▁is ▁a ▁branch ed ▁[ 4 ] tri ang ul ane ; ▁it ▁consists ▁of ▁one ▁additional ▁cy clo prop ane ▁attached ▁to ▁the ▁central ▁ring ▁of ▁a ▁[ 3 ] tri ang ul ane ▁chain . ▁ ▁References ▁▁▁▁ ▁Category : H ydro car b ons ▁Category : C yc lo prop anes ▁Category : S pi ro ▁comp ounds <0x0A> </s> ▁Sy ed ▁J al al ud