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Muonium atom addition to pyridine and to the pyridinium cation
Author(s) -
Rhodes Christopher J.,
Morris Harry,
Reid Ivan D.
Publication year - 2001
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.863
Subject(s) - muonium , chemistry , pyridinium , pyridine , protonation , radical , hydrogen atom , reactivity (psychology) , yield (engineering) , photochemistry , ion , atom (system on chip) , hydrogen , electron paramagnetic resonance , medicinal chemistry , crystallography , group (periodic table) , organic chemistry , nuclear magnetic resonance , medicine , materials science , alternative medicine , physics , pathology , computer science , metallurgy , embedded system
Muonium atoms are found to add mainly to the N‐atom and to the ortho and meta positions in pyridine in almost equal amounts, giving pyridinyl and 2‐azacyclohexadienyl radicals and 3‐azacyclohexadienyl radicals, respectively (no addition was observed at the para site); on protonation, as in a sample of PyH + BF 4 − , the reactivity follows the positive charge density, being enhanced for addition to the N (H + ) position, reduced for the ortho / meta positions, and now conferring a significant yield of the para isomer. These results for genuine reactions of hydrogen atoms are discussed in view of studies of radical formation in these materials, made using EPR spectroscopy, when they are exposed to γ‐rays in cryogenic matrices, for which mechanisms involving charge‐neutralization of initial radical ions are proposed. Copyright © 2001 John Wiley & Sons, Ltd.