Aspects of the CH5N2 potential energy surface: ions CH3NHNH+, CH3NNH2+ and CH2NHNH2+ and radicals CH2NHNH2 studied by theory and experiment

Garderen, Harold F. van; Ruttink, Paul J.A.; Burgers, Peter C.; McGibbon, Graham A.; Terlouw, Johan K.

doi:10.1016/0168-1176(92)80061-5

Cited by 74 publications

(43 citation statements)

References 30 publications

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“…The mass spectra reported below were obtained on a ZAB-R spectrometer with BEIE2 geometry (37). We have examined the spectra of ions from the ion source and, additionally, metastable ion (MI) mass spectra to get more detailed information about the most energetically favourable dissociation pathways of the molecular and daughter ions.…”

Section: Unimolecular Reactions Of Ions Derived From 6-8mentioning

confidence: 99%

The thermolysis of ε-halodisilanes: a preference for 1,2-Si Si → O rearrangement or Si—O cleavage over Si=O bond formation

Roos¹,

McGibbon²,

Brook³

1996

Can. J. Chem.

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Tris(trimethylsily1)-2,2,2-trifluoroethoxysilane 6, tris(trimethylsily1)-2-fluoroethoxysilane 7, and tris(trimethylsily1)-2-chloroethoxysilane 8 were synthesized and characterized by 'H, "C and '9Si NMR, IR spectroscopy, and EI and CI mass spectrometry. Thermodynamic considerations would suggest that, as a result of the driving force provided by the formation of a Si-F or Si-Cl bond, the thermolyses of these compounds would lead to the formation of bis(trimethylsily1)silanone 4. To examine this question, gas chromatography -mass spectrometry was as used a detection technique for products resulting from the high-pressure thermolyses of 6-8. The elimination of (Me,Si),SiCl appears to be the major thermolytic pathway of decomposition for 8 at ambient or higher pressures, although it is accompanied by the formation of other products, some of which could have arisen from the addition of various halosilanes to a silanone. Neither 6 nor 7 thermolyzed cleanly; the former compound was essentially unreactive under the thermolysis temperatures used (850°C). Of the products produced in the thermolysis of 7, no evidence for the formation of the silanone was obtained. Independently, mass spectrometry was used to study unimolecular reactions of molecular ions derived from 6-8. The major route to solitary ions appears to involve a 1,2-trimethylsilyl migration from Si to 0 (9+10) prior to decomposition, for example, of the mlz 346 parent ion in the decomposition of 6. The preparation of the ionized silanone may be a minor pathway. Some of the other fragmentation pathways for 6-8 are discussed. Key words: gas phase thermolysis, ion rearrangements, silyl group migration, silanone, halosilane.RCsume : On a synthCtisC le tris(trimtthylsily1)-2,2,2-trifluorosilane 6, le tris(trimCthylsily1)-2-fluoroCthoxysilane 7, et les tris(trimCthylsily1)-2-chloroCthoxysilane, 8, et on les a caractCrists par la RMN du 'H, du ',c et du 2 9~i , par la spectoscopie IR et par spectromCtrie de masse sous IC et IE. Les considtrations thermodynamiques portent h penser que la thermolyse de ces composCs pourrait conduire i la formation de bis(trimCthylsilyl)silanone, 4, en raison de la force directrice crCC par la formation des liaisons Si-F ou Si-Cl. Pour vCrifier cette hypothese, on a utilisC comme technique de dktection, la spectromCtrie de masse couplCe h la chromatographie en phase gazeuse, pour les produits rksultant des thermolyses h haute pression des composCs 6 8 . L'Climination du (Me3Si),SiC1 semble &tre le processus thermolytique principal de dCcomposition du composC 8 h tempkrature ambiante ou h de plus hautes pressions, bien qu'il se forme d'autres produits dont quelques uns proviennent de l'addition de divers halosilanes sur la silanone. Ni le composC 6 ni le composC 7 ne subissent nettement la thermolyse; le premier composC ne rCagit pas du tout aux tempkratures de thermolyse utilisCes (850°C). On n'a pas pu mettre en Cvidence la prisence de silanone parmi les produits rCsultants de la thermolyse du composC 7. D'une f a~o n indepe...

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Section: Unimolecular Reactions Of Ions Derived From 6-8mentioning

confidence: 99%

The thermolysis of ε-halodisilanes: a preference for 1,2-Si Si → O rearrangement or Si—O cleavage over Si=O bond formation

Roos¹,

McGibbon²,

Brook³

1996

Can. J. Chem.

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“…Authentic samples of the halohydrins 3-and 4-chloro-2-methylbutan-2-ol, 3-and 4-bromo-2-methylbutan-2-ol, and 1-chloro-2-methylbutan-2-ol were analyzed on the above instruments and also on the Varian 920FT GC-FTICR mass spectrometer at the MOE and the McMaster University ZAB-R instrument [12].…”

Section: Methodsmentioning

confidence: 99%

“…The prominent m/z 43 peak undoubtedly represents the acetyl cation, CH 3 C=O + [15]. Tandem mass spectrometry experiments [15] performed using the ZAB-R instrument [12] indicate that this ion is likely formed by the route depicted in Scheme 3.…”

Section: Identification Of the Disinfection By-products Dbp-a Dbp-bmentioning

confidence: 99%

Identification of Halohydrins as Potential Disinfection By‐Products in Treated Drinking Water

Jobst

Taguchi

Bowen

et al. 2011

International Journal of Spectroscopy

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In 2001, two potential disinfection by-products (DBPs) were tentatively identified as 1-aminoxy-1-chlorobutan-2-ol (DBP-A) and its bromo analogue (DBP-B) (Taguchi 2001). Subsequently it became clear, by consulting an updated version of the NIST database, that their mass spectra are close to those of the halohydrins 4-chloro-2-methylbutan-2-ol and 3-bromo-2-methylbutan-2-ol. To establish the structures of these DBPs, additional mass spectrometric experiments, including Fourier transform ion cyclotron resonance (FTICR), were performed on treated drinking water samples and authentic halohydrin standards. It appears that DBP-A is 3-chloro-2-methylbutan-2-ol and that DBP-B is its bromo analogue. DBP-B has been detected in ozonated waters containing bromide. Our study also shows that these DBPs can be laboratory artefacts, generated by the reaction of residual chlorine in the sample with 2-methyl-2-butene, the stabilizer in the CH 2 Cl 2 used for extraction. This was shown by experiments using CH 2 Cl 2 stabilized with deuterium labelled 2-methyl-2-butene. Quenching any residual chlorine in the drinking water sample with sodium thiosulfate minimizes the formation of these artefacts.

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“…The experiments were performed with the VG Analytical ZAB-R mass spectrometer of BEE geometry (B, magnet; E, electric sector) [11] equipped with a standard chemical ionization source operating at 120 • C. The repeller voltage was held close to 0 V and the primary ionization was accomplished with 100 eV electrons. Gaseous acrylonitrile and CO 2 in a ca.…”

Section: Methodsmentioning

confidence: 99%

The acrylonitrile dimer ion: A study of its dissociation via self-catalysis, self-protonation and cyclization into the pyrimidine radical cation

Ervasti¹,

Jobst²,

Burgers³

et al. 2007

International Journal of Mass Spectrometry

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Large energy barriers prohibit the rearrangement of solitary acrylonitrile ions, CH 2 CHC N•+ , into their more stable hydrogen-shift isomers CH 2 C C NH•+ or CH CH-C NH •+ . This prompted us to examine if these isomerizations occur by self-catalysis in acrylonitrile dimer ions. Such ions, generated by chemical ionization experiments of acrylonitrile with an excess of carbon dioxide, undergo five dissociations in the s time frame, as witnessed by peaks at m/z 53, 54, 79, 80 and 105 in their metastable ion mass spectrum. Collision experiments on these product ions, deuterium labeling, and a detailed computational analysis using the CBS-QB3 model chemistry lead to the following conclusions: (i) the m/z 54 ions are ions CH 2 CHC NH + generated by self-protonation in ion-dipole stabilized hydrogen-bridged dimer ions [CH 2 CHC N· · ·H-C(C N)CH 2 ]•+ and [CH 2 CHC N· · ·H-C(H)C(H)C N]•+ ; the proton shifts in these ions are associated with a small reverse barrier; (ii) dissociation of the Hbridged ions into CH 2 C C NH•+ or CH CH-C NH •+ by self-catalysis is energetically feasible but kinetically improbable: experiment shows that the m/z 53 ions are CH 2 CHC N•+ ions, generated by back dissociation; (iii) the peaks at m/z 79, 80 and 105 correspond with the losses of HCN, C 2 H 2 and H• , respectively. The calculations indicate that these ions are generated from dimer ions that have adopted the (much more stable) covalently bound "head-to-tail" structure [CH 2 CHC N-C(H 2 )C(H)C N]•+ ; experiments indicate that the m/z 79 (C 5 H 5 N) and m/z 105 (C 6 H 6 N 2 ) ions have linear structures but the m/z 80 (C 4 H 4 N 2 ) ions consist of ionized pyrimidine in admixture with its stable pyrimidine-2-ylidene isomer. Acrylonitrile is a confirmed species in interstellar space and our study provides experimental and computational evidence that its dimer radical cation yields the ionized prebiotic pyrimidine molecule.

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Aspects of the CH5N2 potential energy surface: ions CH3NHNH+, CH3NNH2+ and CH2NHNH2+ and radicals CH2NHNH2 studied by theory and experiment

Cited by 74 publications

References 30 publications

The thermolysis of ε-halodisilanes: a preference for 1,2-Si Si → O rearrangement or Si—O cleavage over Si=O bond formation

The thermolysis of ε-halodisilanes: a preference for 1,2-Si Si → O rearrangement or Si—O cleavage over Si=O bond formation

Identification of Halohydrins as Potential Disinfection By‐Products in Treated Drinking Water

The acrylonitrile dimer ion: A study of its dissociation via self-catalysis, self-protonation and cyclization into the pyrimidine radical cation

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