Thermochemistry of Organic and Heteroorganic Species. Part 13. Structural Aspects and Thermochemical Approach to Isomerization and Fragmentation of Negative Ions. Simple Bond Cleavage and Hydrogen Rearrangement Processes

ChemInform ◽  
2006 ◽  
Vol 37 (25) ◽  
Author(s):  
Dmitry Ponomarev ◽  
Viatcheslav Takhistov
Keyword(s):  
Bond Cleavage ◽  
Negative Ions ◽  
Rearrangement Processes ◽  
Hydrogen Rearrangement ◽  
Structural Aspects

Studies in Negative-Ion Mass Spectrometry. XII. Electron Attachment to a Series of Bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)-metal Complexes

1979 ◽  
Vol 32 (11) ◽  
pp. 2405 ◽  
Author(s):  
DR Dakternieks ◽  
IW Fraser ◽  
JL Garnett ◽  
IK Gregor
Keyword(s):  
Mass Spectra ◽  
Electron Attachment ◽  
Negative Ions ◽  
Fragmentation Pathway ◽  
Negative Ion ◽  
Metal Fluoride ◽  
Class A ◽  
Negative Ion Mass Spectrometry ◽  
Fragment Ions ◽  
Rearrangement Processes

Results of electron-attachment reactions in the gas phase as well as negative-ion mass spectra are given for a series of bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)metal(1) complexes, (ML2), with the divalent metals MgII, MnII, Co11, Nil1, Cu11 and ZnII. While molecular, [ML2]- or [ML2]-, and ligand, [L]-, ions are present in the negative-ion mass spectra, the lability of the ligand C-F and C-CF3 bonds enables rearrangement processes involving fluorine atom transfers to become significant in the decompositions of both molecular and fragment ions, particularly for the class (a) metals, for which significant yields of [MLF2] and [MLF] negative ions were obtained. Thus, the predominant fragmentation pathway for such metal-containing complexes, for which metastable peaks have been assigned, occurs in the sequence [ML2]- -(*) → (MLF2]- - (8) → [L]- or alternatively [ML2]- -(*) → (MLF2]- - (8) → [L]- with the latter fragmentation in these sequences involving the elimination of the divalent metal fluoride, MF2.

Rearrangement processes of negative ions in the gas phase: [M  Hal]− ions in halogenated azobenzenes. Resonance stabilization of negative ions

1995 ◽  
Vol 30 (2) ◽  
pp. 275-281 ◽  
Author(s):  
M. V. Muftakhov ◽  
Yu. V. Vasil'ev ◽  
V. A. Masunov ◽  
V. V. Takhistov ◽  
D. A. Ponomarev
Keyword(s):  
Gas Phase ◽  
Negative Ions ◽  
Resonance Stabilization ◽  
Rearrangement Processes

Structural aspects of osmoregulation in porphyra

1978 ◽  
Vol 36 (2) ◽  
pp. 412-413
Author(s):  
C. Wiencke ◽  
A. Lauchli
Keyword(s):  
Culture Medium ◽  
Point Of View ◽  
Chemical Fixation ◽  
Cellular Organization ◽  
Osmotic Adaptation ◽  
Osmotic Balance ◽  
Activity Of Enzymes ◽  
Osmotic Agents ◽  
Vacuolar System ◽  
Structural Aspects

Osmoregulatory mechanisms in algae were investigated mainly from a physiological point of view (KAUSS 1977, HELLEBUST 1976). In Porphyra two osmotic agents, i. e. floridoside/isofloridoside (KAUSS 1968) and certain ions, such as K+ and Na+(EPPLEY et al. 1960) are considered for osmotic balance. Accumulations of ions (particularly Na+) in the cytoplasm during osmotic adaptation is improbable, because the activity of enzymes is generally inhibited by high ionic concentrations (FLOWERS et al. 1977).The cellular organization of Porphyra was studied with special emphasis on the development of the vacuolar system under different hyperosmotic conditions. Porphyra was cultivated at various strengths of the culture medium ASP 12 (PROVASOLI 1961) ranging from normal to 6 times concentrated (6x) culture medium. Por electron microscopy freeze fracturing was used (specimens fixed in 2% glutaraldehyde and incubated in 30% glycerol, preparation in a BALZERS BA 360 M apparatus), because chemical fixation gave poor results.

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