Computational Chemistry Comparison and Benchmark DataBase Release 22 (May 2022) Standard Reference Database 101 National Institute of Standards and Technology
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Relative enthalpies of isomers - Comparison of 0K enthalpies (kJ mol^-1)

Isomers of C₅H₈

index	Species	CAS number	Name	Relative experimental enthalpy (kJ mol-1)	sketch
a	C5H8	78795	1,3-Butadiene, 2-methyl-	38.1
b	C5H8	142290	Cyclopentene	0.0
c	C5H8	157404	Spiropentane
d	C5H8	185944	Bicyclo[2.1.0]pentane
e	C5H8	311751	Bicyclo[1.1.1]pentane
f	C5H8	591935	1,4-Pentadiene	63.4
g	C5H8	591957	1,2-Pentadiene	102.3
h	C5H8	591968	2,3-Pentadiene	94.4
i	C5H8	598254	1,2-Butadiene, 3-methyl-	89.8
j	C5H8	627190	1-pentyne
k	CH3CCCH2CH3	627214	2-Pentyne
l	C5H8	693867	Ethenylcyclopropane
m	C5H8	1120565	Cyclobutane, methylene-	86.7
n	C5H8	1574410	1,3-Pentadiene, (Z)-	44.8
o	C5H8	2004708	1,3-Pentadiene, (E)-	38.1