Selected ATcT [1, 2] enthalpy of formation based on version 1.176 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.172 to include species related to Criegee intermediates that are involved in several ongoing studies[4].

1-Ethynyl-2-propyn-1-ylidene

Formula: HCCCCCH (g, triplet)

CAS RN: 882068-94-2

ATcT ID: 882068-94-2*1

SMILES: C#C[C]C#C

InChI: InChI=1S/C5H2/c1-3-5-4-2/h1-2H

InChIKey: ONLBGIDTQSBRIM-UHFFFAOYSA-N

Hills Formula: C5H2

2D Image:

Aliases: HCCCCCH; 1-Ethynyl-2-propyn-1-ylidene; 117992-78-6; 2,4-Pentadiynylidene; Penta-1,2-dien-4-yn-1-ylium-3-ide; 2,4-Pentadiyn-1-ylidene; 1800066-01-6; 1,2,3,4-Pentatetraene-1,5-diyl

Relative Molecular Mass: 62.0694 ± 0.0040

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
727.0	734.1	± 1.7	kJ/mol

3D Image of HCCCCCH (g, triplet)

spin ON spin OFF

Top contributors to the provenance of Δ_fH° of HCCCCCH (g, triplet)

The 6 contributors listed below account for 92.1% of the provenance of Δ_fH° of HCCCCCH (g, triplet).

Please note: The list is limited to 20 most important contributors or, if less, a number sufficient to account for 90% of the provenance. The Reference acts as a further link to the relevant references and notes for the measurement. The Measured Quantity is normaly given in the original units; in cases where we have reinterpreted the original measurement, the listed value may differ from that given by the authors. The quoted uncertainty is the a priori uncertainty used as input when constructing the initial Thermochemical Network, and corresponds either to the value proposed by the original authors or to our estimate; if an additional multiplier is given in parentheses immediately after the prior uncertainty, it corresponds to the factor by which the prior uncertainty needed to be multiplied during the ATcT analysis in order to make that particular measurement consistent with the prevailing knowledge contained in the Thermochemical Network.

Contribution (%)	TN ID	Reaction	Measured Quantity	Reference
64.5	9011.1	5 CH4 (g) → HCCCCCH (g, triplet) + 9 H2 (g)	Δ_rH°(0 K) = 1059.82 ± 2.00 kJ/mol	Klippenstein 2017
9.6	9012.2	HCCCCCH (g, triplet) + CH2 (g, triplet) → 2 HCCCH (g, triplet)	Δ_rH°(0 K) = -7.19 ± 1.0 kcal/mol	Ruscic G4
7.9	9012.1	HCCCCCH (g, triplet) + CH2 (g, triplet) → 2 HCCCH (g, triplet)	Δ_rH°(0 K) = -6.84 ± 1.1 kcal/mol	Ruscic G3X
3.8	9012.4	HCCCCCH (g, triplet) + CH2 (g, triplet) → 2 HCCCH (g, triplet)	Δ_rH°(0 K) = -5.79 ± 1.0 (×1.576) kcal/mol	Ruscic CBS-n
3.8	9012.3	HCCCCCH (g, triplet) + CH2 (g, triplet) → 2 HCCCH (g, triplet)	Δ_rH°(0 K) = -8.89 ± 1.3 (×1.215) kcal/mol	Ruscic CBS-n
2.1	9012.5	HCCCCCH (g, triplet) + CH2 (g, triplet) → 2 HCCCH (g, triplet)	Δ_rH°(0 K) = -9.42 ± 0.9 (×2.327) kcal/mol	Ruscic W1RO

Top 10 species with enthalpies of formation correlated to the Δ_fH° of HCCCCCH (g, triplet)

Please note: The correlation coefficients are obtained by renormalizing the off-diagonal elements of the covariance matrix by the corresponding variances.
The correlation coefficient is a number from -1 to 1, with 1 representing perfectly correlated species, -1 representing perfectly anti-correlated species, and 0 representing perfectly uncorrelated species.

Correlation Coefficent (%)	Species Name	Formula	Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units	Relative Molecular Mass	ATcT ID
100.0	1-Ethynyl-2-propyn-1-ylidene	HCCCCCH (g)	727.0	734.1	± 1.7	kJ/mol	62.0694 ± 0.0040	882068-94-2*0
80.4	1-Ethynyl-2-propyn-1-ylidene	HCCCCCH (g, singlet C2v)	787.5	792.5	± 2.1	kJ/mol	62.0694 ± 0.0040	882068-94-2*21
80.4	1-Ethynyl-2-propyn-1-ylidene	HCCCCCH (g, singlet)	787.5	792.9	± 2.1	kJ/mol	62.0694 ± 0.0040	882068-94-2*2
79.2	1,3-Pentadiyne-1.5-diyl	CH2CCCC (g)	783.8	787.3	± 2.1	kJ/mol	62.0694 ± 0.0040	117992-81-1*0
68.7	1,2-Pentadien-4-ynylidene	HCCCHCC (g)	791.3	794.0	± 2.4	kJ/mol	62.0694 ± 0.0040	195524-67-5*0
65.0	1-Ethynyl-2-propyn-1-ylium-1-yl	[HCCCCCH]+ (g)	1537.2	1540.8	± 2.6	kJ/mol	62.0688 ± 0.0040	217822-76-9*0
64.9	1-Ethynyl-2-propyn-1-ylidene	HCCCCCH (g, singlet Cs)	796.1	801.0	± 2.6	kJ/mol	62.0694 ± 0.0040	882068-94-2*22
52.1	2-Ethynyl-2-cyclopropen-1-ylidene	HCCC(CCH) (g)	726.1	727.4	± 3.2	kJ/mol	62.0694 ± 0.0040	117992-84-4*0
48.7	2-Cyclopropen-1-ylideneethenylidene	CCC(CHCH) (g)	807.2	808.8	± 3.4	kJ/mol	62.0694 ± 0.0040	195524-69-7*0
47.0	1-Ethynyl-2-propyn-1-ylidene anion	[HCCCCCH]- (g)	584.2	589.3	± 3.5	kJ/mol	62.0699 ± 0.0040	217822-70-3*0

Most Influential reactions involving HCCCCCH (g, triplet)

Please note: The list, which is based on a hat (projection) matrix analysis, is limited to no more than 20 largest influences.

Influence Coefficient	TN ID	Reaction	Measured Quantity	Reference
1.000	9013.1	HCCCCCH (g) → HCCCCCH (g, triplet)	Δ_rH°(0 K) = 0 ± 0 cm-1	Ruscic W1RO, Ruscic G4, Ruscic CBS-n
0.732	9023.9	CH2CCCC (g) → HCCCCCH (g, triplet)	Δ_rH°(0 K) = -13.53 ± 0.35 kcal/mol	Thimmakondu 2019
0.674	9015.7	HCCCCCH (g, triplet) → HCCCCCH (g, singlet C2v)	Δ_rH°(0 K) = 14.12 ± 0.35 kcal/mol	Thimmakondu 2019
0.657	9011.1	5 CH4 (g) → HCCCCCH (g, triplet) + 9 H2 (g)	Δ_rH°(0 K) = 1059.82 ± 2.00 kJ/mol	Klippenstein 2017
0.400	9008.5	[HCCCCCH]- (g) → HCCCCCH (g, triplet)	Δ_rH°(0 K) = 1.460 ± 0.050 eV	Ruscic W1RO
0.280	9005.1	HCCCCCH (g, triplet) → [HCCCCCH]+ (g)	Δ_rH°(0 K) = 8.36 ± 0.03 (×1.242) eV	Reusch 2019
0.269	9008.2	[HCCCCCH]- (g) → HCCCCCH (g, triplet)	Δ_rH°(0 K) = 1.537 ± 0.061 eV	Ruscic G4
0.243	9005.6	HCCCCCH (g, triplet) → [HCCCCCH]+ (g)	Δ_rH°(0 K) = 8.414 ± 0.040 eV	Ruscic W1RO
0.243	9005.7	HCCCCCH (g, triplet) → [HCCCCCH]+ (g)	Δ_rH°(0 K) = 8.417 ± 0.040 eV	Lam 2021, est unc
0.166	9012.2	HCCCCCH (g, triplet) + CH2 (g, triplet) → 2 HCCCH (g, triplet)	Δ_rH°(0 K) = -7.19 ± 1.0 kcal/mol	Ruscic G4
0.140	9023.8	CH2CCCC (g) → HCCCCCH (g, triplet)	Δ_rH°(0 K) = -14.24 ± 0.80 kcal/mol	Thimmakondu 2019
0.138	9008.1	[HCCCCCH]- (g) → HCCCCCH (g, triplet)	Δ_rH°(0 K) = 1.489 ± 0.085 eV	Ruscic G3X
0.137	9012.1	HCCCCCH (g, triplet) + CH2 (g, triplet) → 2 HCCCH (g, triplet)	Δ_rH°(0 K) = -6.84 ± 1.1 kcal/mol	Ruscic G3X
0.129	9015.6	HCCCCCH (g, triplet) → HCCCCCH (g, singlet C2v)	Δ_rH°(0 K) = 14.94 ± 0.80 kcal/mol	Thimmakondu 2019
0.118	9008.3	[HCCCCCH]- (g) → HCCCCCH (g, triplet)	Δ_rH°(0 K) = 1.466 ± 0.092 eV	Ruscic CBS-n
0.073	9005.3	HCCCCCH (g, triplet) → [HCCCCCH]+ (g)	Δ_rH°(0 K) = 8.392 ± 0.073 eV	Ruscic G4
0.069	9005.5	HCCCCCH (g, triplet) → [HCCCCCH]+ (g)	Δ_rH°(0 K) = 8.415 ± 0.075 eV	Ruscic CBS-n
0.066	9012.4	HCCCCCH (g, triplet) + CH2 (g, triplet) → 2 HCCCH (g, triplet)	Δ_rH°(0 K) = -5.79 ± 1.0 (×1.576) kcal/mol	Ruscic CBS-n
0.066	9012.3	HCCCCCH (g, triplet) + CH2 (g, triplet) → 2 HCCCH (g, triplet)	Δ_rH°(0 K) = -8.89 ± 1.3 (×1.215) kcal/mol	Ruscic CBS-n
0.059	9008.4	[HCCCCCH]- (g) → HCCCCCH (g, triplet)	Δ_rH°(0 K) = 1.350 ± 0.090 (×1.445) eV	Ruscic CBS-n

References

1		B. Ruscic, R. E. Pinzon, M. L. Morton, G. von Laszewski, S. Bittner, S. G. Nijsure, K. A. Amin, M. Minkoff, and A. F. Wagner, Introduction to Active Thermochemical Tables: Several "Key" Enthalpies of Formation Revisited. J. Phys. Chem. A 108, 9979-9997 (2004) [DOI: 10.1021/jp047912y]
2		B. Ruscic, R. E. Pinzon, G. von Laszewski, D. Kodeboyina, A. Burcat, D. Leahy, D. Montoya, and A. F. Wagner, Active Thermochemical Tables: Thermochemistry for the 21^st Century. J. Phys. Conf. Ser. 16, 561-570 (2005) [DOI: 10.1088/1742-6596/16/1/078]
3		B. Ruscic and D. H. Bross, Active Thermochemical Tables (ATcT) values based on ver. 1.176 of the Thermochemical Network (2024); available at ATcT.anl.gov
4		T. L. Nguyen et al, ongoing studies (2024)
5		B. Ruscic, Uncertainty Quantification in Thermochemistry, Benchmarking Electronic Structure Computations, and Active Thermochemical Tables. Int. J. Quantum Chem. 114, 1097-1101 (2014) [DOI: 10.1002/qua.24605]
6		B. Ruscic and D. H. Bross, Thermochemistry Computer Aided Chem. Eng. 45, 3-114 (2019) [DOI: 10.1016/B978-0-444-64087-1.00001-2]

Formula

The aggregate state is given in parentheses following the formula, such as: g - gas-phase, cr - crystal, l - liquid, etc.

Uncertainties

The listed uncertainties correspond to estimated 95% confidence limits, as customary in thermochemistry (see, for example, Ruscic [5] and Ruscic and Bross[6]).
Note that an uncertainty of ± 0.000 kJ/mol indicates that the estimated uncertainty is < ± 0.000₅ kJ/mol.

Website Functionality Credits

The reorganization of the website was developed and implemented by David H. Bross (ANL).
The find function is based on the complete Species Dictionary entries for the appropriate version of the ATcT TN.
The molecule images are rendered by Indigo-depict.
The XYZ renderings are based on Jmol: an open-source Java viewer for chemical structures in 3D. http://www.jmol.org/.

Acknowledgement

This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under Contract No. DE-AC02-06CH11357.