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/cc-pVTZ

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-5	-7	allene	propyne	2
C4H6			-37	-51	1,2-Butadiene	1,3-Butadiene	14
C4H6			3	3	1,2-Butadiene	1-Butyne	-0
C4H6			-40	-49	Cyclobutene	1,3-Butadiene	10
C4H6			-80	-82	1-Methylcyclopropene	1,2-Butadiene	2
C4H6			47	42	Methylenecyclopropane	1-Methylcyclopropene	5
C3H6O			-112	-110	Oxetane	Propanal	-2