C-H bond dissociation energy of malononitrile

Daniel J. Goebbert, Luis Velarde, Dmitry Khuseynov, Andrei M Sanov

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

The C-H bond dissociation energies of closed-shell molecules decrease with increasing stability of the resulting radicals. From the electron affinity of the dicyanomethyl radical, •CH(CN)2, EA[•CH(CN) 2]=2.88± 0.01 eV, measured by photoelectron imaging of the CH(CN)2 - anion, and the acidity/electron affinity thermodynamic cycle, we obtained the C-H bond dissociation enthalpy of malononitrile, CH2(CN)2, DH298[H-CH(CN) 2]=87 ± 2 kcal/mol. This result is compared to the corresponding value for acetonitrile, DH298(H-CH2CN)=93 ± 2 kcal/mol, determined from a similar measurement of EA(•CH2CN) = 1.53 ( 0.01 eV. The relative weakness of the C-H bonds in malononitrile and acetonitrile, compared to most closed-shell neutral organic molecules, is attributed to π-resonance stabilization of the unpaired electrons in •CH(CN)2 and •CH2CN.

Original languageEnglish (US)
Pages (from-to)792-795
Number of pages4
JournalJournal of Physical Chemistry Letters
Volume1
Issue number4
DOIs
StatePublished - Feb 18 2010

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malononitrile
Electron affinity
Acetonitrile
dissociation
methylidyne
Molecules
Photoelectrons
electron affinity
Acidity
acetonitrile
Anions
Enthalpy
Negative ions
Stabilization
Thermodynamics
thermodynamic cycles
Imaging techniques
energy
Electrons
acidity

Keywords

  • Kinetics
  • Spectroscopy

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

C-H bond dissociation energy of malononitrile. / Goebbert, Daniel J.; Velarde, Luis; Khuseynov, Dmitry; Sanov, Andrei M.

In: Journal of Physical Chemistry Letters, Vol. 1, No. 4, 18.02.2010, p. 792-795.

Research output: Contribution to journalArticle

Goebbert, Daniel J. ; Velarde, Luis ; Khuseynov, Dmitry ; Sanov, Andrei M. / C-H bond dissociation energy of malononitrile. In: Journal of Physical Chemistry Letters. 2010 ; Vol. 1, No. 4. pp. 792-795.
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N2 - The C-H bond dissociation energies of closed-shell molecules decrease with increasing stability of the resulting radicals. From the electron affinity of the dicyanomethyl radical, •CH(CN)2, EA[•CH(CN) 2]=2.88± 0.01 eV, measured by photoelectron imaging of the CH(CN)2 - anion, and the acidity/electron affinity thermodynamic cycle, we obtained the C-H bond dissociation enthalpy of malononitrile, CH2(CN)2, DH298[H-CH(CN) 2]=87 ± 2 kcal/mol. This result is compared to the corresponding value for acetonitrile, DH298(H-CH2CN)=93 ± 2 kcal/mol, determined from a similar measurement of EA(•CH2CN) = 1.53 ( 0.01 eV. The relative weakness of the C-H bonds in malononitrile and acetonitrile, compared to most closed-shell neutral organic molecules, is attributed to π-resonance stabilization of the unpaired electrons in •CH(CN)2 and •CH2CN.

AB - The C-H bond dissociation energies of closed-shell molecules decrease with increasing stability of the resulting radicals. From the electron affinity of the dicyanomethyl radical, •CH(CN)2, EA[•CH(CN) 2]=2.88± 0.01 eV, measured by photoelectron imaging of the CH(CN)2 - anion, and the acidity/electron affinity thermodynamic cycle, we obtained the C-H bond dissociation enthalpy of malononitrile, CH2(CN)2, DH298[H-CH(CN) 2]=87 ± 2 kcal/mol. This result is compared to the corresponding value for acetonitrile, DH298(H-CH2CN)=93 ± 2 kcal/mol, determined from a similar measurement of EA(•CH2CN) = 1.53 ( 0.01 eV. The relative weakness of the C-H bonds in malononitrile and acetonitrile, compared to most closed-shell neutral organic molecules, is attributed to π-resonance stabilization of the unpaired electrons in •CH(CN)2 and •CH2CN.

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