Structural and electronic characterisation of the organometallic distonic ion (C6H6)Fe+(p-C6H4)·

The loss of ammonia from the metastable molecular ions of cyclic cyano compounds has been examined with the use of deuterium labeling and tandem mass spectrometry. Loss of ammonia is significant for ionized cyanocyclohexane, 1-methyl-, 4-methyl-, 4-cyano-and 4-phenyl-cyanocyclohexanes, 4-cyanopiperidine, cyanocycloheptane and 2-cyanonorbornane. By contrast, loss of ammonia is of minor importance (or absent) for the molecular ions of cyanocyclopentane, 2-methyl-cyanocyclohexane, 1-phenyl-cyanocyclohexane, 1-cyanocyclohexene, 4-cyanotetrahydrothiopyran, 2-cyano-5-norbornene and isocyanocyclohexane. Deuterium labeling of cyanocyclohexane reveals the occurrence of an H-shift from the 4-position to the cyano function, followed by a 1,2-H shift from the 1-position to the C-atom of the newly-formed–CNH group. Subsequently, a series of H-shifts leads to a distonic ion that is formulated as an N-protonated methylamine attached to a cyclohexadienyl radical. Loss of ammonia ensues and leads to ionized toluene as indicated by collision-induced dissociation experiments. For 4-phenyl-cyanocyclohexane, the metastable ions of the cis- and trans-isomers display, essentially, the same unimolecular chemistry. Briefly, the labeling of 4-phenyl-cyanocyclohexane indicates the following: (i) the H atom at the 4-position of the cyclohexane ring is incorporated, to a minor extent, in the ammonia molecule, (ii) loss of NHD2 predominates in the reactions of the molecular ions of 2,2,6,6-d4-4-phenyl-cyanocyclohexane and (iii) the ionized 3,3,5-d3-labeled species expels mainly NH2D. In addition, the metastable molecular ions of the 4-[d5-phenyl]-cyanocyclohexane expel NH3 and NH2D in a ratio of 35:65. A mechanistic scheme is proposed that is consistent with the labeling results for 4-phenyl-cyanocyclohexane as well as the indicated formation of ionized 4-methylbiphenyl as the product ion of ammonia loss.

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Bimolecular reactions involving the radical site of the distonic ion ·CH2CH2CH2CO+

Rapid Communications in Mass Spectrometry ◽

10.1002/rcm.1290070516 ◽

1993 ◽

Vol 7 (5) ◽

pp. 392-399 ◽

Cited By ~ 18

Author(s):

Krista M. Stirk ◽

Rebecca L. Smith ◽

Joe C. Orlowski ◽

Hilkka I. Kenttämaa

Keyword(s):

Bimolecular Reactions ◽

Radical Site ◽

Distonic Ion

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Gas-phase reactions of the sulphur distonic ion with alkenes

Organic Mass Spectrometry ◽

10.1002/oms.1210280816 ◽

1993 ◽

Vol 28 (8) ◽

pp. 919-920 ◽

Cited By ~ 10

Author(s):

Margot W. van Amsterdam ◽

Paul O. Staneke ◽

Steen Ingemann ◽

Nico M. M. Nibbering

Keyword(s):

Gas Phase ◽

Gas Phase Reactions ◽

Distonic Ion

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A gas-phase study of ligand effects on the reactivity of organometallic distonic ion Fe(p-benzyne)+˙

Rapid Communications in Mass Spectrometry ◽

10.1002/(sici)1097-0231(19990430)13:8<645::aid-rcm533>3.0.co;2-s ◽

1999 ◽

Vol 13 (8) ◽

pp. 645-649 ◽

Cited By ~ 3

Author(s):

Young C. Xu ◽

Quan Chen ◽

Sara K. Poehlein ◽

Ben S. Freiser

Keyword(s):

Gas Phase ◽

Ligand Effects ◽

Phase Study ◽

Distonic Ion

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Differentiation of Ionised Benzimidazole from its Isomeric α-Distonic Ion by Collision-Induced Dissociation and Neutralisation—Reionisation Mass Spectrometry

European Journal of Mass Spectrometry ◽

10.1255/ejms.775 ◽

2005 ◽

Vol 11 (4) ◽

pp. 381-387 ◽

Cited By ~ 3

Author(s):

Thanasis Karapanayiotis ◽

Richard D. Bowen

Keyword(s):

Mass Spectra ◽

Radical Cations ◽

Time Frame ◽

Careful Consideration ◽

Collision Induced Dissociation ◽

Doubly Charged Ions ◽

Doubly Charged ◽

Ion Collision ◽

Charged Ions ◽

Distonic Ion

Ionised benzimidazole and its isomeric α-distonic ion (or ionised ylid) have been examined by recording their metastable ion, collision-induced dissociation and neutralisation–reionisation mass spectra. These tautomers may be distinguished by careful consideration of key features of the collision-induced dissociation spectra, with or without prior neutralisation and reionisation. Formation of doubly-charged ions by charge stripping occurs preferentially when the α-distonic ion is subjected to collision. This α-distonic ion survives neutralisation and reionisation, thus establishing that the corresponding ylid is stable on the microsecond time frame. The effects of benzannulation on the ease of differentiation of classical and distonic radical cations derived from biologically important heterocycles are considered.

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