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Characterization of isomeric C 4 H 5 − anions in the gas phase; theory and experiment
Author(s) -
de Visser Sam P.,
van der Horst Eric,
de Koning Leo J.,
van der Hart Wim J.,
Nibbering Nico M. M.
Publication year - 1999
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/(sici)1096-9888(199904)34:4<303::aid-jms753>3.0.co;2-c
Subject(s) - chemistry , deprotonation , methyl formate , delocalized electron , carbanion , reactivity (psychology) , medicinal chemistry , ion , formate , methanol , carbon fibers , pyridine , computational chemistry , photochemistry , organic chemistry , catalysis , medicine , materials science , alternative medicine , pathology , composite number , composite material
Experimental and theoretical studies of gas‐phase isomeric C 4 H 5 − anions have beenperformed. Deprotonation of 1,2‐butadiene is expected to occurmainly at the 3‐position, giving an anion which also isobtained after deprotonation of 2‐butyne. The gas‐phaseacidities (Δ G acid ° )of 1,2‐butadiene and 2‐butyne have been determined fromthe equilibria with methanol and pyridine and have led to Δ G acid ° =1574±10 kJ mol −1 and Δ G acid ° =1596±10 kJ mol −1 , respectively.Deprotonated 1,2‐butadiene and 2‐butyne have been foundto react similarly with N 2 O, neo‐pentyl nitrite andmethyl formate. These reactivity studies have indicated that thecharge of the anion is delocalized over 2 carbon atoms. Ab initio calculations have been applied to isomeric C 4 H 5 − anions and have confirmed this hypothesis.The calculations have shown the existence of six stable C 4 H 5 − anions. The reaction betweencarbon‐3 deprotonated 1,3‐butadiene with methyl formatehas shown that the 2‐buta‐1,3‐dienyl anion has adelocalized charge at carbon‐1 and carbon‐3. Copyright© 1999 John Wiley & Sons, Ltd.