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: QCISD/6-31+G**

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-2	-7	allene	propyne	4
C4H6			-13	-17	1,2-Butadiene	2-Butyne	4
C4H6			-80	-82	1-Methylcyclopropene	1,2-Butadiene	3
C4H6			-56	-49	Cyclobutene	1,3-Butadiene	-6
C4H6			-52	-51	1,2-Butadiene	1,3-Butadiene	-1
C4H6			6	3	1,2-Butadiene	1-Butyne	3
C4H6			48	42	Methylenecyclopropane	1-Methylcyclopropene	7
C3H6O			-114	-110	Oxetane	Propanal	-4
C4H8			-30	-33	cyclobutane	1-Butene	2
C5H8			24	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	-1
C5H8			-51	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	1