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: CCSD(T)/6-31G*

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-4	-7	allene	propyne	3
C4H6			-49	-51	1,2-Butadiene	1,3-Butadiene	2
C4H6			-50	-49	Cyclobutene	1,3-Butadiene	-0
C4H6			6	3	1,2-Butadiene	1-Butyne	3
C3H6O			-116	-110	Oxetane	Propanal	-6
C4H8			-25	-33	cyclobutane	1-Butene	7