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On the nature of the ‘methoxy’ cation
Author(s) -
Bouma Willem J.,
Nobes Ross H.,
Radom Leo
Publication year - 1982
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210170705
Subject(s) - oxonium ion , chemistry , dimethyl ether , radical ion , dissociation (chemistry) , ion , ether , ab initio , fragmentation (computing) , bond dissociation energy , hydroxymethyl , photochemistry , polyatomic ion , carbene , computational chemistry , organic chemistry , methanol , computer science , catalysis , operating system
Ab initio molecular orbital calculations with large, polarization basis sets and incorporating valence‐electron correlation have been used to investigate the structure of the [COH 3 ] + ion formed at threshold from fragmentation of dimethyl ether in the mass spectrometer. The results indicate that this ion is the hydroxymethyl cation, [CH 2 OH] + , formed with excess energy in a two‐step rearrangement‐dissociation process involving an initial 1,2‐hydrogen shift in the dimethyl ether radical cation to yield an oxonium ion intermediate, [CH 2 OHCH 3 ] +˙ , followed by CO bond cleavage. The intermediate oxonium ion is predicted to lie slightly lower in energy than the dimethyl ether radical cation and represents a stable, previously unreported [C 2 H 6 O] +˙ isomer. It is suggested that at high energies, decomposition of the dimethyl ether radical cation involves dissociation followed by rearrangement.