CCCBDB listing of experimental data page 2

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Property	Value	Uncertainty	units	Reference
Hfg(298.15K)	568.52	5.00	kJ mol^-1	Gurvich
Hfg(0K)	565.00	5.00	kJ mol^-1	Gurvich
Entropy (298.15K)	209.73		J K^-1 mol^-1	Gurvich
Integrated Heat Capacity (0 to 298.15K)	9.86		kJ mol^-1	Gurvich
Heat Capacity (298.15K)	39.65		J K^-1 mol^-1	Gurvich

Mode Number	Symmetry	Frequency			Intensity			Comment	Description
Mode Number	Symmetry	Fundamental(cm^-1)	Harmonic(cm^-1)	Reference	(km mol^-1)	unc.	Reference	Comment	Description
1	Σ	3299		VEEL5					CH stretch
2	Σ	1841		VEEL5					CC stretch
3	Π	372		VEEL5					bend

Description	Value	unc.	Connectivity				Reference	Comment
Description	Value	unc.	Atom 1	Atom 2	Atom 3	Atom 4	Reference	Comment
rCH	1.047		1	3			1998Kuc	rs value
rCC	1.217		1	2			1998Kuc	rs value
aHCC	180		2	1	3		1998Kuc

Atom	x (Å)	y (Å)	z (Å)
C1	0.0000	0.0000	0.0000
C2	0.0000	0.0000	-1.2165
H3	0.0000	0.0000	1.0465

	C1	C2	H3
C1		1.2165	1.0465
C2	1.2165		2.2631
H3	1.0465	2.2631

	Computational Chemistry Comparison and Benchmark DataBase Release 22 (May 2022) Standard Reference Database 101 National Institute of Standards and Technology
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State	Config	State description	Conf description	Exp. min.	Dipole (Debye)				Reference	comment	Point Group	Components
State	Config	State description	Conf description	Exp. min.	x	y	z	total	Reference	comment	Point Group	dipole	quadrupole
1	1	²Σ	C_∞v	True							C_∞v	1	1
1	2	²A^'	C_s								C_s	2	3

squib	reference	DOI
1984Say/Ves:2247	Saykally, R.; Veseth, L. "Laser magnetic resonance rotational spectroscopy of 2Sigma radicals: Ethynyl (CCH)." Journal of Chemical Physics. 80, 2247-2255 (1984)	10.1063/1.447001
1998Kuc	K Kuchitsu(ed) "Structure of Free Polyatomic Molecules - Basic Data" Springer, Berlin, 1998	10.1007/978-3-642-45748-7
Gurvich	Gurvich, L.V.; Veyts, I. V.; Alcock, C. B., Thermodynamic Properties of Individual Substances, Fouth Edition, Hemisphere Pub. Co., New York, 1989
VEEL5	M.E. Jacox, Vibrational and Electronic Energy Levels of Polyatomic Transient Molecules, J. Phys. Chem.Ref. Data, Monograph 3 (1994) (updated data in NIST Chemistry Webbook - http://webbook.nist.gov/chemistry/
webbook	NIST Chemistry Webbook (http://webbook.nist.gov/chemistry)	10.18434/T4D303

Bond Type	Count
C#C	1
H-C	1

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Experimental data for C2H- (Ethynyl anion)

Experimental data for C₂H^- (Ethynyl anion)