Gas-phase negative-ion chemistry of diazomethane

DePuy, Charles H.; Doren, Jane M. Van; Gronert, Scott; Kass, Steven R.; Motell, Edwin L.; Ellison, G. Barney; Bierbaum, Veronica M.

doi:10.1021/jo00269a020

Cited by 13 publications

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“…The gas-phase acidity of diazomethane was measured previously in a flowing afterglow device and the enthalpy of deprotonation (373 ± 3 kcal/mol) is in excellent accord with our determination of Δ acid H 298 (H−CHNN) = 372.2 ± 2.1 kcal/mol. Use of the electron affinity, EA(HCNN) = 38.9 ± 0.1 kcal mol -1 , leads to a value for the bond enthalpy of diazomethane, DH 298 (H−CHNN) = 97 ± 2 kcal mol -1 .…”

Section: Thermochemistrysupporting

confidence: 87%

Properties of Diazocarbene [CNN] and the Diazomethyl Radical [HCNN] via Ion Chemistry and Spectroscopy

et al. 1998

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We have used negative ion photoelectron spectroscopy to measure the electron affinities of diazocarbene and the diazomethyl radical: EA(Χ ˜3Σ -CNN) ) 1.771 ( 0.010 eV, EA(Χ ˜2A′′ HCNN) ) 1.685 ( 0.006 eV, and EA(Χ ˜2A′′ DCNN) ) 1.678 ( 0.006 eV. Our experimental findings are accurately reproduced by complete basis set (CBS) ab initio electronic structure calculations: EA(Χ ˜3Σ -CNN) ) 1.83 ( 0.03 eV, EA(Χ ˜2A′′ HCNN) ) 1.69 ( 0.03 eV. We make use of the electron affinities of CNN and HCNN, together with the gas phase acidity of diazomethane, ∆ acid H 298 (HCHN 2 ) ) 372.2 ( 2.1 kcal mol -1 (CBS calculated value ) 373.4 ( 0.7), to find the bond enthalpies of H 2 CNN. We find DH 298 (H-CHN 2 ) equal to 97 ( 2 kcal mol -1 , which closely agrees with the CBS-QCI/APNO-calculated value [DH 298 (H-CHN 2 ) ) 98.5 ( 0.7 kcal mol -1 ]. From proton transfer experiments in a Fourier transform mass spectrometer and a tandem flowing afterglow-selected ion flow tube (FA-SIFT), we find ∆ acid H 298 (HCNN) ) 352 ( 4 kcal mol -1 in agreement with the CBS-QCI/ APNO-calculated value of 351.8 ( 0.7 kcal mol -1 . Use of the experimental electron affinity, EA(CNN), leads to the CH bond enthalpy of the cyanoamino radical, DH 298 (H-CNN) ) 79 ( 4 kcal mol -1 which is in excellent agreement with the CBS-QCI/APNO-calculated value: DH 298 (H-CNN) ) 78.7 ( 0.7 kcal mol -1 . If we adopt the CBS-QCI/APNO value for ∆ f H 298 (CH 2 N 2 ) [64.1 ( 0.7 kcal mol -1 ] as our reference, we obtain ∆ f H 298 (HCN 2 ) ) 110 ( 2 kcal mol -1 and ∆ f H 298 (CN 2 ) ) 136 ( 5 kcal mol -1 , which are again in agreement with the CBS-QCI/APNO values: ∆ f H 298 (HCN 2 ) ) 110.5 ( 0.7 kcal mol -1 and ∆ f H 298 (CN 2 ) ) 138.4 ( 0.7 kcal mol -1 . We recommend revised experimental values for ∆ f H 0 (HCN) ) 30.9 ( 0.7 kcal mol -1 and ∆ f H 298 (HCN) ) 30.8 ( 0.7 kcal mol -1 and find that the reaction CH ( 2 Π) + N 2 f HCN + N ( 4 S) to be slightly endothermic, ∆ rxn H 0 ) 1.6 ( 0.7 kcal mol -1 .

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Section: Thermochemistrysupporting

confidence: 87%

Properties of Diazocarbene [CNN] and the Diazomethyl Radical [HCNN] via Ion Chemistry and Spectroscopy

et al. 1998

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“…Neither reaction was studied calorimetrically. Accordingly, they cannot be compared with the energetics of the reaction of HCN 2 − with CO to form HCCO − and N 2 , a quantity indirectly obtainable from the deprotonation enthalpies of diazomethane 35,36 and ketene 37 .…”

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Thermochemical Considerations of Metal Enolates

Liebman

Slayden

2010

Patai's Chemistry of Functional Groups

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Introduction Group 1: Lithium, Sodium, Potassium, Rubidium and Cesium Group 2: Beryllium, Magnesium, Calcium, Strontium and Barium Group 13: Aluminum, Gallium, Indium and Thallium Group 14: Tin and Lead Group 11: Copper, Silver and Gold Group 12: Zinc, Cadmium and Mercury Group 3: Scandium, Yttrium and the Lanthanides Actinides Group 4: Titanium, Zirconium and Hafnium Group 5: Vanadium, Niobium and Tantalum Group 6: Chromium, Molybdenum and Tungsten Group 7: Manganese and Rhenium Group 8: Iron, Ruthenium and Osmium Group 9: Cobalt, Rhodium and Iridium Group 10: Nickel, Palladium and Platinum

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“…For more basic carbanions such as the anions of 1,3-butadiene (PA = 397 kcal/mol) and 1-methylpyrrole (PA = 386 kcal/mol), there are two reaction channels with CS 2 : addition and sulfur atom abstraction. Addition is the only reaction channel for less basic carbanions such as the anions of nitromethane (PA = 356 kcal/mol) and diazomethane (PA = 373 kcal/mol). − Sulfur atom transfer observed with distonic radical anions 4 (PA = 354 kcal/mol) and 1 1 (PA ≤ 385 kcal/mol) suggests that distonic radical anions are better nucleophiles than the closed shell anions of similar structure and basicity. This is supported by the observations that CO 2 adds to radical anion 4 but does not react with anion 6 .…”

Section: Resultsmentioning

confidence: 99%

Anion-Molecule Approaches to Non-Kekulé Molecules: The Radical Anion of Cyclopentadienylidenetrimethylenemethane and Derivatives

1996

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Cyclopentadienylidenetrimethylenemethane radical anion 4, the one-electron reduction product of the corresponding diradical 3, was generated by a gas phase ion-molecule reaction of 6,6-dimethylfulvene (5) with O•-. Characterization was carried out by isotopic labeling to confirm the distonic structure of the radical anion. The results suggest that negative ion photoelectron spectroscopic experiments can be used to resolve a conflict between theories regarding the nature (singlet or triplet) of the ground state of 3. In reactivity studies, the radical anion 4 is a better nucleophile than its corresponding anion 6, a result similar to that found for the tetramethyleneethane radical anion 1. The basicity of the radical anion 4 has been bracketed at approximately 354 ± 3 kcal/mol. This study contains the first evidence that a distonic radical anion can react as a radical as well as an anion, a result that will lead to further gas phase examination of the radicals in the distonic ion series.

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Gas-phase negative-ion chemistry of diazomethane

Cited by 13 publications

References 0 publications

Properties of Diazocarbene [CNN] and the Diazomethyl Radical [HCNN] via Ion Chemistry and Spectroscopy

Properties of Diazocarbene [CNN] and the Diazomethyl Radical [HCNN] via Ion Chemistry and Spectroscopy

Thermochemical Considerations of Metal Enolates

Anion-Molecule Approaches to Non-Kekulé Molecules: The Radical Anion of Cyclopentadienylidenetrimethylenemethane and Derivatives

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