Translational energy release: Experiment and theory. H2 elimination reactions of small gas phase ions, and correspondence to HH bond activation

Uggerud, Einar

doi:10.1002/(sici)1098-2787(1999)18:5<285::aid-mas1>3.0.co;2-v

Cited by 46 publications

(39 citation statements)

References 159 publications

(47 reference statements)

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“…Near threshold, CH 2 ϭND 2 ϩ and CD 2 ϭNH 2 ϩ both eliminate HD with high selectivity [1], demonstrating that they undergo a formal 1,2-elimination. H 2 eliminations from other CH 2 ϭZH ϩ species (Z ϭ O, S) have similar specificities [1]. However, 1,2 eliminations should violate conservation of orbital symmetry [2], conservation which opposes their synchronous occurrence.…”

mentioning

confidence: 68%

“…The reverse barriers to 1,2-eliminations of H 2 were first attributed to those reactions having to surmount high barriers imposed by conservation of orbital symmetry [5,6]. However, theory later revealed that the transition-state geometries of many 1,2-eliminations strongly resemble CH 3 Z ϩ , i.e., transition states of 1,1-eliminations [1,7]. Presumably this route, although high in energy, is taken to circumvent orbital symmetry constraints [2].…”

mentioning

confidence: 75%

“…This is supplied by the excess energy in the system. This critical energy is substantial, in contrast to that for some allowed H 2 -eliminations [1].…”

Section: The Reaction Coordinate and Reaction Synchronicitymentioning

confidence: 99%

“…This reaction is made feasible by its conservation of orbital symmetry, the energy supplied by formation of the H-H bond, and a favorable geometry of the ion for eliminating H 2 . (J Am Soc Mass Spectrom 2008, 19, 27-32) © 2008 American Society for Mass Spectrometry M ost H 2 -eliminations from cations in the gasphase are 1,1-or 1,2-processes [1]. Near threshold, CH 2 ϭND 2 ϩ and CD 2 ϭNH 2 ϩ both eliminate HD with high selectivity [1], demonstrating that they undergo a formal 1,2-elimination.…”

mentioning

confidence: 99%

“…(J Am Soc Mass Spectrom 2008, 19, 27-32) © 2008 American Society for Mass Spectrometry M ost H 2 -eliminations from cations in the gasphase are 1,1-or 1,2-processes [1]. Near threshold, CH 2 ϭND 2 ϩ and CD 2 ϭNH 2 ϩ both eliminate HD with high selectivity [1], demonstrating that they undergo a formal 1,2-elimination. H 2 eliminations from other CH 2 ϭZH ϩ species (Z ϭ O, S) have similar specificities [1].…”

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confidence: 99%

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Elimination of H₂ from CH₃CH=N⁺HCH₃: A synchronous, concerted 1,4-H₂ elimination

Bowen

McAdoo

2008

J. Am. Soc. Mass Spectrom.

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Most H 2 eliminations from cations in the gas phase are formally 1,1-or 1,2-processes. Larger ring size H 2 eliminations are rare and little studied. Thus, whether the 6-center, 1,4-elimination CH 3 CHϭN ϩ HCH 3 ¡ CH 2 ϭCHN ϩ HϭCH 2 ϩ H 2 is concerted and synchronous, as indicated by isotope effects and predicted by conservation of orbital symmetry, is a significant question. This reaction is characterized here by application of QCI and B3LYP theories. CH bond-breaking and H-H bond-making in this reaction are found by theory to be highly synchronized, consistent with previously established isotope effects and in contrast to "forbidden" 1,2-eliminations from organic cations in the gas phase. This reaction is made feasible by its conservation of orbital symmetry, the energy supplied by formation of the H-H bond, and a favorable geometry of the ion for eliminating H 2 . (J Am

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mentioning

confidence: 68%

mentioning

confidence: 75%

“…This is supplied by the excess energy in the system. This critical energy is substantial, in contrast to that for some allowed H 2 -eliminations [1].…”

Section: The Reaction Coordinate and Reaction Synchronicitymentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Elimination of H₂ from CH₃CH=N⁺HCH₃: A synchronous, concerted 1,4-H₂ elimination

Bowen

McAdoo

2008

J. Am. Soc. Mass Spectrom.

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Nonpolar Dihydrogen Bonds—On a Gliding Scale from Weak Dihydrogen Interaction to Covalent HH in Symmetric Radical Cations [H_nE‐H‐H‐EH_n]⁺

Krapp

Frenking

Uggerud

2008

Chemistry A European J

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The electronic structures and bonding patterns for a new class of radical cations, [HnE-H-H-EHn]+ (EHn=element hydride, E=element of Groups 15-18), have been investigated by applying quantum-chemical methods. All structures investigated give rise to symmetric potential energy minimum structures. We envisage clear periodic trends. The H--H bond length is shorter for elements toward the bottom of the periodic table of elements, and a short H--H bond corresponds to accumulation of electron density in the central H--H region. All [HnE-H-H-EHn]+ of Groups 15-17 are thermodynamically unstable towards loss of either H2 or H. The barriers for these dissociations are rather low. The Group 18 congeners, except E=Xe, appear to be global minima of the respective potential energy surfaces. The findings are discussed in terms of H2 bond activation, and a general mechanistic scheme for the standard reduction process 2H+ + 2e(-) --> H2 is given. Finally, it is proposed that some of the symmetric radical cations are likely to be observed in mass spectrometric or matrix isolation experiments.

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ChemInform Abstract: Translational Energy Release Experiment and Theory: H₂ Elimination Reactions of Small Gas Phase Ions and Correspondence to H—H Bond Activation

Uggerud

2000

ChemInform

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Translational energy release: Experiment and theory. H2 elimination reactions of small gas phase ions, and correspondence to HH bond activation

Cited by 46 publications

References 159 publications

Elimination of H₂ from CH₃CH=N⁺HCH₃: A synchronous, concerted 1,4-H₂ elimination

Elimination of H₂ from CH₃CH=N⁺HCH₃: A synchronous, concerted 1,4-H₂ elimination

Nonpolar Dihydrogen Bonds—On a Gliding Scale from Weak Dihydrogen Interaction to Covalent HH in Symmetric Radical Cations [H_nE‐H‐H‐EH_n]⁺

ChemInform Abstract: Translational Energy Release Experiment and Theory: H₂ Elimination Reactions of Small Gas Phase Ions and Correspondence to H—H Bond Activation

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Translational energy release: Experiment and theory. H2 elimination reactions of small gas phase ions, and correspondence to HH bond activation

Cited by 46 publications

References 159 publications

Elimination of H2 from CH3CH=N+HCH3: A synchronous, concerted 1,4-H2 elimination

Elimination of H2 from CH3CH=N+HCH3: A synchronous, concerted 1,4-H2 elimination

Nonpolar Dihydrogen Bonds—On a Gliding Scale from Weak Dihydrogen Interaction to Covalent HH in Symmetric Radical Cations [HnE‐H‐H‐EHn]+

ChemInform Abstract: Translational Energy Release Experiment and Theory: H2 Elimination Reactions of Small Gas Phase Ions and Correspondence to H—H Bond Activation

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Elimination of H₂ from CH₃CH=N⁺HCH₃: A synchronous, concerted 1,4-H₂ elimination

Elimination of H₂ from CH₃CH=N⁺HCH₃: A synchronous, concerted 1,4-H₂ elimination

Nonpolar Dihydrogen Bonds—On a Gliding Scale from Weak Dihydrogen Interaction to Covalent HH in Symmetric Radical Cations [H_nE‐H‐H‐EH_n]⁺

ChemInform Abstract: Translational Energy Release Experiment and Theory: H₂ Elimination Reactions of Small Gas Phase Ions and Correspondence to H—H Bond Activation