Pyridine, protonated

• Formula: C₅H₆N⁺
• Molecular weight: 80.1073
• Information on this page:
  • Reaction thermochemistry data
  • References
  • Notes
• Other data available:
  • Ion clustering data
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Reaction thermochemistry data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: Michael M. Meot-Ner (Mautner) and Sharon G. Lias

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

C₅H₆N⁺ +  = (C₅H₆N⁺  )

By formula: C₅H₆N⁺ + C₅H₅N = (C₅H₆N⁺  C₅H₅N)

Quantity	Value	Units	Method	Reference	Comment
rH°	105.	kJ/mol	PHPMS	Meot-Ner (Mautner), 1992	gas phase
rH°	103.	kJ/mol	PHPMS	Meot-Ner M. and Sieck, 1983	gas phase
rH°	110.	kJ/mol	HPMS	Holland and Castleman, 1982	gas phase
rH°	99.2	kJ/mol	PHPMS	Meot-Ner (Mautner), 1979	gas phase
rH°	99.2	kJ/mol	PHPMS	Meot-Ner (Mautner), 1979	gas phase
Quantity	Value	Units	Method	Reference	Comment
rS°	124.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1992	gas phase
rS°	118.	J/mol*K	PHPMS	Meot-Ner M. and Sieck, 1983	gas phase
rS°	134.	J/mol*K	HPMS	Holland and Castleman, 1982	gas phase
rS°	120.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1979	gas phase
rS°	120.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1979	gas phase

C₅H₆N⁺ +  = (C₅H₆N⁺  )

By formula: C₅H₆N⁺ + C₁₂H₂₄O₆ = (C₅H₆N⁺  C₁₂H₂₄O₆)

Bond type: Hydrogen bonds with polydentate bonding in positive ions

Quantity	Value	Units	Method	Reference	Comment
rH°	180. ± 20.	kJ/mol	PHPMS	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated
Quantity	Value	Units	Method	Reference	Comment
rS°	180.	J/mol*K	N/A	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated

Free energy of reaction

rG° (kJ/mol)	T (K)	Method	Reference	Comment
67.	550.	PHPMS	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated

C₅H₆N⁺ +  = (C₅H₆N⁺  )

By formula: C₅H₆N⁺ + C₆H₁₄O = (C₅H₆N⁺  C₆H₁₄O)

Bond type: Hydrogen bonds of the type NH+-O between organics

Quantity	Value	Units	Method	Reference	Comment
rH°	98.3	kJ/mol	PHPMS	Meot-Ner, 1984	gas phase; Entropy change calculated or estimated
Quantity	Value	Units	Method	Reference	Comment
rS°	130.	J/mol*K	N/A	Meot-Ner, 1984	gas phase; Entropy change calculated or estimated

Free energy of reaction

rG° (kJ/mol)	T (K)	Method	Reference	Comment
33.	500.	PHPMS	Meot-Ner, 1984	gas phase; Entropy change calculated or estimated

C₅H₆N⁺ +  = (C₅H₆N⁺  )

By formula: C₅H₆N⁺ + H₂O = (C₅H₆N⁺  H₂O)

Bond type: Hydrogen bond (positive ion to hydride)

Quantity	Value	Units	Method	Reference	Comment
rH°	67.4	kJ/mol	PHPMS	Meot-Ner M. and Sieck, 1983	gas phase
rH°	62.8	kJ/mol	PHPMS	Davidson, Sunner J., et al., 1979	gas phase
Quantity	Value	Units	Method	Reference	Comment
rS°	113.	J/mol*K	PHPMS	Meot-Ner M. and Sieck, 1983	gas phase
rS°	107.	J/mol*K	PHPMS	Davidson, Sunner J., et al., 1979	gas phase

C₅H₆N⁺ +  = (C₅H₆N⁺  )

By formula: C₅H₆N⁺ + C₆H₁₄O₃ = (C₅H₆N⁺  C₆H₁₄O₃)

Bond type: Hydrogen bonds with polydentate bonding in positive ions

Quantity	Value	Units	Method	Reference	Comment
rH°	132.	kJ/mol	PHPMS	Meot-Ner (Mautner), 1983	gas phase; diglyme
Quantity	Value	Units	Method	Reference	Comment
rS°	153.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1983	gas phase; diglyme

C₅H₆N⁺ +  = (C₅H₆N⁺  )

By formula: C₅H₆N⁺ + C₄H₁₀O₂ = (C₅H₆N⁺  C₄H₁₀O₂)

Bond type: Hydrogen bonds with polydentate bonding in positive ions

Quantity	Value	Units	Method	Reference	Comment
rH°	106.	kJ/mol	PHPMS	Meot-Ner (Mautner), 1983	gas phase; glyme
Quantity	Value	Units	Method	Reference	Comment
rS°	131.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1983	gas phase; glyme

(C₅H₆N⁺  2) +  = (C₅H₆N⁺  3)

By formula: (C₅H₆N⁺  2C₅H₅N) + C₅H₅N = (C₅H₆N⁺  3C₅H₅N)

Quantity	Value	Units	Method	Reference	Comment
rH°	56.9	kJ/mol	HPMS	Holland and Castleman, 1982	gas phase; Entropy change is questionable
Quantity	Value	Units	Method	Reference	Comment
rS°	159.	J/mol*K	HPMS	Holland and Castleman, 1982	gas phase; Entropy change is questionable

(C₅H₆N⁺  2) +  = (C₅H₆N⁺  3)

By formula: (C₅H₆N⁺  2H₂O) + H₂O = (C₅H₆N⁺  3H₂O)

Bond type: Hydrogen bond (positive ion to hydride)

Quantity	Value	Units	Method	Reference	Comment
rH°	35.	kJ/mol	PHPMS	Davidson, Sunner J., et al., 1979	gas phase
Quantity	Value	Units	Method	Reference	Comment
rS°	82.0	J/mol*K	PHPMS	Davidson, Sunner J., et al., 1979	gas phase

C₅H₆N⁺ +  = (C₅H₆N⁺  )

By formula: C₅H₆N⁺ + C₅H₁₂O₂ = (C₅H₆N⁺  C₅H₁₂O₂)

Bond type: Hydrogen bonds with polydentate bonding in positive ions

Quantity	Value	Units	Method	Reference	Comment
rH°	111.	kJ/mol	PHPMS	Meot-Ner (Mautner), 1983	gas phase
Quantity	Value	Units	Method	Reference	Comment
rS°	150.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1983	gas phase

C₅H₆N⁺ +  = (C₅H₆N⁺  )

By formula: C₅H₆N⁺ + C₁₀H₂₀O₅ = (C₅H₆N⁺  C₁₀H₂₀O₅)

Bond type: Hydrogen bonds with polydentate bonding in positive ions

Quantity	Value	Units	Method	Reference	Comment
rH°	172.	kJ/mol	PHPMS	Meot-Ner (Mautner), 1983	gas phase
Quantity	Value	Units	Method	Reference	Comment
rS°	178.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1983	gas phase

(C₅H₆N⁺  ) +  = (C₅H₆N⁺  2)

By formula: (C₅H₆N⁺  H₂O) + H₂O = (C₅H₆N⁺  2H₂O)

Bond type: Hydrogen bond (positive ion to hydride)

Quantity	Value	Units	Method	Reference	Comment
rH°	40.	kJ/mol	PHPMS	Davidson, Sunner J., et al., 1979	gas phase
Quantity	Value	Units	Method	Reference	Comment
rS°	82.0	J/mol*K	PHPMS	Davidson, Sunner J., et al., 1979	gas phase

C₅H₆N⁺ +  = (C₅H₆N⁺  )

By formula: C₅H₆N⁺ + C₈H₁₈O₄ = (C₅H₆N⁺  C₈H₁₈O₄)

Bond type: Hydrogen bonds with polydentate bonding in positive ions

Quantity	Value	Units	Method	Reference	Comment
rH°	145.	kJ/mol	PHPMS	Meot-Ner (Mautner), 1983	gas phase
Quantity	Value	Units	Method	Reference	Comment
rS°	160.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1983	gas phase

C₅H₆N⁺ +  = (C₅H₆N⁺  )

By formula: C₅H₆N⁺ + C₈H₁₆O₄ = (C₅H₆N⁺  C₈H₁₆O₄)

Bond type: Hydrogen bonds with polydentate bonding in positive ions

Quantity	Value	Units	Method	Reference	Comment
rH°	151.	kJ/mol	PHPMS	Meot-Ner (Mautner), 1983	gas phase
Quantity	Value	Units	Method	Reference	Comment
rS°	167.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1983	gas phase

C₅H₆N⁺ +  = (C₅H₆N⁺  )

By formula: C₅H₆N⁺ + C₄H₁₀O = (C₅H₆N⁺  C₄H₁₀O)

Bond type: Hydrogen bonds of the type NH+-O between organics

Quantity	Value	Units	Method	Reference	Comment
rH°	94.1	kJ/mol	PHPMS	Meot-Ner (Mautner), 1983	gas phase
Quantity	Value	Units	Method	Reference	Comment
rS°	138.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1983	gas phase

(C₅H₆N⁺  ) +  = (C₅H₆N⁺  2)

By formula: (C₅H₆N⁺  C₅H₅N) + C₅H₅N = (C₅H₆N⁺  2C₅H₅N)

Quantity	Value	Units	Method	Reference	Comment
rH°	52.7	kJ/mol	HPMS	Holland and Castleman, 1982	gas phase
Quantity	Value	Units	Method	Reference	Comment
rS°	124.	J/mol*K	HPMS	Holland and Castleman, 1982	gas phase

References

Go To: Top, Reaction thermochemistry data, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Meot-Ner (Mautner), 1992
Meot-Ner (Mautner), M., Intermolecular Forces in Organic Clusters, J. Am. Chem. Soc., 1992, 114, 9, 3312, https://doi.org/10.1021/ja00035a024 . [all data]

Meot-Ner M. and Sieck, 1983
Meot-Ner M.; Sieck, L.W., The Ionic Hydrogen Bond. 1. Sterically Hindered Bonds. Solvation and Clustering of Sterically Hindered Amines and Pyridines, J. Am. Chem. Soc., 1983, 105, 10, 2956, https://doi.org/10.1021/ja00348a005 . [all data]

Holland and Castleman, 1982
Holland, P.M.; Castleman, A.W., The Thermochemical Properties of Gas - Phase Transition Metal Ion Complexes, J. Chem. Phys., 1982, 76, 8, 4195, https://doi.org/10.1063/1.443497 . [all data]

Meot-Ner (Mautner), 1979
Meot-Ner (Mautner), M., Ion Thermochemistry of Low Volatility Compounds in the Gas Phase. II. Intrinsic Basicities and Hydrogen Bonded Dimers of Nitrogen Heterocyclics and Nucleic Bases, J. Am. Chem. Soc., 1979, 101, 9, 2396, https://doi.org/10.1021/ja00503a027 . [all data]

Meot-Ner (Mautner), 1983
Meot-Ner (Mautner), M., The Ionic Hydrogen Bond. 3. Multiple and -CH+...O- Bonds. Complexes of Ammonium Ions with Polyethers and Crown Ethers, J. Am. Chem. Soc., 1983, 105, 15, 4912, https://doi.org/10.1021/ja00353a012 . [all data]

Meot-Ner, 1984
Meot-Ner, (Mautner)M., The Ionic Hydrogen Bond and Ion Solvation. 1. -NH+ O-, -NH+ N- and -OH+ O- Bonds. Correlations with Proton Affinity. Deviations Due to Structural Effects, J. Am. Chem. Soc., 1984, 106, 5, 1257, https://doi.org/10.1021/ja00317a015 . [all data]

Davidson, Sunner J., et al., 1979
Davidson, W.R.; Sunner J.; Kebarle, P., Hydrogen Bonding of Water to Onium Ions. Hydration of Substituted Pyridinium Ions and Related Systems, J. Am. Chem. Soc., 1979, 101, 7, 1675, https://doi.org/10.1021/ja00501a005 . [all data]

Notes

Go To: Top, Reaction thermochemistry data, References

• Symbols used in this document:
  

  T	Temperature
  rG°	Free energy of reaction at standard conditions
  rH°	Enthalpy of reaction at standard conditions
  rS°	Entropy of reaction at standard conditions

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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