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: MP2/cc-pV(T+d)Z

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-19	-7	allene	propyne	-12
C4H6			-50	-51	1,2-Butadiene	1,3-Butadiene	1
C4H6			-43	-49	Cyclobutene	1,3-Butadiene	6
C4H6			-31	-17	1,2-Butadiene	2-Butyne	-14
C4H6			-66	-82	1-Methylcyclopropene	1,2-Butadiene	17
C4H6			41	42	Methylenecyclopropane	1-Methylcyclopropene	-0