نتایج جستجو برای: y aromatic counter ions

تعداد نتایج: 703932  

Journal: :Journal of the American Society for Mass Spectrometry 2012
Roman A Zubarev David M Good Mikhail M Savitski

Radical a* ions appear in electron capture dissociation mass spectra sporadically, but sometimes with high intensity. Mechanistically, radical a ions are hypothesized to arise due to thermodynamically disadvantaged charge solvation on the backbone nitrogen (instead of carbonyl), which upon neutralization produces a hypervalent group instantly fragmenting into a radical b* and conventional y' io...

Journal: :Physical chemistry chemical physics : PCCP 2017
Michael Gatchell Rudy Delaunay Giovanna D'Angelo Arkadiusz Mika Kostiantyn Kulyk Alicja Domaracka Patrick Rousseau Henning Zettergren Bernd A Huber Henrik Cederquist

We report on studies of collisions between 3 keV Ar+ projectile ions and neutral targets of isolated 1,3-butadiene (C4H6) molecules and cold, loosely bound clusters of these molecules. We identify molecular growth processes within the molecular clusters that appears to be driven by knockout processes and that could result in the formation of (aromatic) ring structures. These types of reactions ...

2015
Ioannis Tiritiris Willi Kantlehner

In the title salt, C16H34N5O3 (+)·C24H20B(-), the C-N bond lengths in the cation are 1.3368 (16), 1.3375 (18) and 1.3594 (17) Å, indicating partial double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal-planar geometry and the positive charge is delocal-ized in the CN3 plane. In the crystal, weak C-H⋯O contacts are observed between neighbouring guani...

Journal: :Physical chemistry chemical physics : PCCP 2014
G V Baryshnikov R R Valiev N N Karaush B F Minaev

A series of planar hetero[8]circulenes and their doubly charged ions are studied by the NICS and GIMIC methods to interpret the aromatic properties of these high symmetry species. In accordance with the performed calculations all studied hetero[8]circulenes are found to be nonaromatic compounds because paratropic and diatropic ring-currents are completely canceled yielding almost zero net curre...

2003
ELVERA EHRENFELD SARA Jo MARBLE ALTON MEISTER

The synthesis of y-glutamylhydroxamic acid from glutamine and hydroxylamine is catalyzed by glutamine synthetase in the presence of adenosine diphosphate, inorganic phosphate, and magnesium ions (l), and also by other enzyme preparations (2,3) that do not exhibit a requirement for nucleotides or metal ions. The synthesis of y-glutamylhydroxamic acid from glutamic acid and hydroxylamine that is ...

Journal: :The Journal of biological chemistry 1963
E EHRENFELD S J MARBLE A MEISTER

The synthesis of y-glutamylhydroxamic acid from glutamine and hydroxylamine is catalyzed by glutamine synthetase in the presence of adenosine diphosphate, inorganic phosphate, and magnesium ions (l), and also by other enzyme preparations (2,3) that do not exhibit a requirement for nucleotides or metal ions. The synthesis of y-glutamylhydroxamic acid from glutamic acid and hydroxylamine that is ...

2009
Milad Gabro Roger A. Lalancette Ivan Bernal

The title ionic compound, C(2)H(10)N(2) (2+)·2Cl(-), crystallizes with a center of symmetry within the cation. Each of the positively charged ammonium ends of the mol-ecule is trigonally hydrogen bonded to three different chloride counter-ions, while each of the chloride ions is trigonally hydrogen bonded to three different ethyl-enediammonium cations. The hydrogen-bonding network leads to stab...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2014
Boris Galabov Gergana Koleva Svetlana Simova Boriana Hadjieva Henry F Schaefer Paul von Ragué Schleyer

Our computational and experimental investigation of the reaction of anisole with Cl2 in nonpolar CCl4 solution challenges two fundamental tenets of the traditional SEAr (arenium ion) mechanism of aromatic electrophilic substitution. Instead of this direct substitution process, the alternative addition-elimination (AE) pathway is favored energetically. This AE mechanism rationalizes the preferre...

Journal: :The planetary science journal 2021

Titan's ionosphere contains a plethora of hydrocarbons and nitrile cations anions as measured by the Ion Neutral Mass Spectrometer Cassini Plasma (CAPS) onboard spacecraft. Data from CAPS Beam (IBS) sensor have been examined for five close encounters Titan during 2009. The high relative velocity with respect to cold ions in allows IBS function mass spectrometer. Positive ion masses between 170 ...

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