Computational Chemistry Comparison and Benchmark DataBase Release 22 (May 2022) Standard Reference Database 101 National Institute of Standards and Technology
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Tautomer energy comparison

using model chemistry: MP3=FULL/6-31+G**

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-0	-7	allene	propyne	6
C4H6			-75	-82	1-Methylcyclopropene	1,2-Butadiene	7
C4H6			-51	-49	Cyclobutene	1,3-Butadiene	-2
C4H6			-53	-51	1,2-Butadiene	1,3-Butadiene	-1
C4H6			9	3	1,2-Butadiene	1-Butyne	6
C4H6			48	42	Methylenecyclopropane	1-Methylcyclopropene	6
C3H6O			-107	-110	Oxetane	Propanal	3
C4H8			-27	-33	cyclobutane	1-Butene	6
C4H6S			-1	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-5
C5H8			25	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	0
C5H8			65	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	1
C5H8			-52	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	-0
C5H10			-6	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-0
C5H10			-21	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	8