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: LSDA/aug-cc-pVDZ

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			18	-7	allene	propyne	25
C4H6			-27	-51	1,2-Butadiene	1,3-Butadiene	24
C4H6			30	3	1,2-Butadiene	1-Butyne	27
C4H6			-1	-17	1,2-Butadiene	2-Butyne	16
C4H6			-6	-49	Cyclobutene	1,3-Butadiene	43
C4H6			-62	-82	1-Methylcyclopropene	1,2-Butadiene	20
C4H6			52	42	Methylenecyclopropane	1-Methylcyclopropene	11
C4H6S			-5	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-9
C5H8			39	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	14
C5H8			58	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-6
C5H10			-14	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-9
C5H10			-1	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	28