Reappraisal of the spin-forbidden unimolecular decay of the methoxy cation†

Aschi, Massimiliano; Harvey, Jeremy N.; Schalley, Christoph A.; Schröder, Detlef; Schwarz, Helmut

doi:10.1039/a708642c

Cited by 42 publications

(50 citation statements)

References 13 publications

(5 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It has been demonstrated experimentally that triplet CH 3 O may decay onto the singlet CH 2 OH potential surface and decompose to HCO and H 2``o n the¯y'' (Burgers & Holmes, 1984). More recent studies (experiment and high level quantum chemical calculations) con®rm this (Yarkony, 1992;Aschi et al, 1998). All important aspects of the current view of the [C,H 3 ,O] PES are summarized in Fig.…”

Section: Translational Energy Releasementioning

confidence: 81%

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

Uggerud

1999

Mass Spectrom. Rev.

View full text Add to dashboard Cite

Section: Translational Energy Releasementioning

confidence: 81%

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

Uggerud

1999

Mass Spectrom. Rev.

View full text Add to dashboard Cite

“…67 The latter species is isoelectronic with CH 3 O + for which MECPs leading to H 2 loss have been described. 47,66,68 We have not considered this mechanism here, given our prediction ͑below͒ that pyrolysis of methyl azide leads primarily to singlet products.…”

Section: Pyrolysis Of Methyl Azidementioning

confidence: 94%

“…65,66 An alternative lower-energy mechanism involves 1,1 loss of H 2 to form CNH through 1 TS d , 87.0 kcal/ mol above 1 CH 2 NH, followed by isomerization of CNH to HCN through 1 TS e , located 51.5 kcal/ mol above 1 CH 2 NH͒.…”

Section: Pyrolysis Of Methyl Azidementioning

confidence: 99%

Understanding the rate of spin-forbidden thermolysis of HN3 and CH3N3

Besora

Harvey

2008

The Journal of Chemical Physics

View full text Add to dashboard Cite

The pyrolysis of the simplest azides HN(3) and CH(3)N(3) has been studied computationally. Nitrogen extrusion leads to the production of NH or CH(3)N. The azides have singlet ground states but the nitrenes CH(3)N and NH have triplet ground states. The competition between spin-allowed decomposition to the excited state singlet nitrenes and the spin-forbidden N(2) loss is explored using accurate electronic structure methods (CASSCF/cc-pVTZ and MR-AQCC/cc-pVTZ) as well as statistical rate theories. Nonadiabatic rate theories are used for the dissociation leading to the triplet nitrenes. For HN(3), (3)NH formation is predicted to dominate at low energy, and the calculated rate constant agrees very well with energy-resolved experimental measurements. Under thermal conditions, however, the singlet and triplet pathways are predicted to occur competitively, with the spin-allowed product increasingly favored at higher temperatures. For CH(3)N(3) thermolysis, spin-allowed dissociation to form (1)CH(3)N should largely dominate at all temperatures, with spin-forbidden formation of (3)CH(3)N almost negligible. Singlet methyl nitrene is very unstable and should rearrange to CH(2)NH immediately upon formation, and the latter species may lose H(2) competitively with vibrational cooling, depending on temperature and pressure.

show abstract

“…21) (133). Such an isomerization is known to represent a key elementary reaction in the overall unimolecular decomposition of the triplet methoxy cation (134,135). It has been suggested to involve a spin-flopping through two minimum energy crossing points (135).…”

Section: Dehydrogenation Of Triplet Cationsmentioning

confidence: 99%

Dihydrogen Catalysis: A Remarkable Avenue in the Reactivity of Molecular Hydrogen

Asatryan

Ruckenstein

2014

Catalysis Reviews

View full text Add to dashboard Cite

Molecular hydrogen is the simplest and most abundant compound in the universe and is involved in numerous industrial chemical processes. In conventional chemistry, dihydrogen typically plays the role of a reductant and a reagent for homogeneous and heterogeneous hydrogenation processes such as the industrial and enzymatic ammonia formation, reduction of metallic ores and hydrogenation of unsaturated fats and oils. However, there are also processes in which molecular hydrogen participates as promoter, and even as catalyst. The catalytic role of the dihydrogen in free-valence migration in irradiated polymers and the interstellar isomerization of the formyl cation (protonated carbon monoxide) are well-documented examples of such processes. Recently, this issue has received new attention. Dihydrogen has been shown to play the role of a dehydrogenation catalyst (involving particularly metallocomplexes and inorganic materials), a relay (pass-on) transfer molecular agent and a transporter of protons.This review article, combined with original results, is focused on the mechanisms of the chemical processes where dihydrogen demonstrates catalytic behavior. We will call these processes (with somewhat broader meaning of the term) "dihydrogen catalysis" (DHC) which also includes the reactions mediated by transition metal dihydrides. Dihydrides are tentatively considered as pre-activated dihydrogen, coordinated to a metal center or implanted into a solid surface/support. DHC reactions are classified into five major reaction types: (i) dihydrogen-assisted relay transport of H-atoms (H2-RT); (ii) dihydrogen-assisted stepwise relay transport of H-atoms or of a free valence (sH2-RT); (iii) dihydrogen-assisted proton transport (H2-PT); (iv) dihydrogen-assisted dehydrogenation (H2-DeH); and (v) pre-activated dehydrogenation (PA-DeH). The classification of these mechanisms is Color versions of one or more of the figures in the article can be found online at www. tandfonline.com/lctr. 403 Downloaded by [George Mason University] at 02:43 28 September 2014 R. Asatryan and E. Ruckensteinbased on a detailed analysis of numerous potential energy surfaces studied by DFT and ab initio methods in conjunction with available experimental data. The H2-RT, H2-DeH, and PA-DeH processes occur via cyclic transition states. The relay H2-RT transport involves the H-H-H triad linked to both H-donor and H-acceptor centers, whereas the transition state ring in the H2-DeH dehydrogenation processes involves a H-H-H-H tetrad with the dihydrogen catalyst located in the middle. The H2-PT mechanism provides the transport of a proton mediated by dihydrogen combined in a triangular (H 3 + )-carrier unit. There are also practically important processes stimulated by dihydrogen such as the hydrogen spillover and hydrogen build-up in electronics, in which the catalytic role of dihydrogen is ambiguous, either because of the uncertainties in mechanisms, or prevailing traditional views. Some examples are briefly discussed in the framework of the concept of dihydrogen ...

show abstract

Reappraisal of the spin-forbidden unimolecular decay of the methoxy cation†

Cited by 42 publications

References 13 publications

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

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

Understanding the rate of spin-forbidden thermolysis of HN3 and CH3N3

Dihydrogen Catalysis: A Remarkable Avenue in the Reactivity of Molecular Hydrogen

Contact Info

Product

Resources

About