TY - JOUR
T1 - Indenone and cyclopentadienone energetics via mass spectrometry and computations
T2 - Are these species antiaromatic or "merely" nonaromatic?
AU - Fattahi, Alireza
AU - Liebman, Joel F.
AU - Miranda, Margarida S.
AU - Morais, Victor M.F.
AU - Matos, M. Agostinha R.
AU - Lis, Lev
AU - Kass, Steven R.
N1 - Funding Information:
Support from the National Science Foundation and the Minnesota Supercomputer Institute for Advanced Computational Research are gratefully acknowledged.
PY - 2014/8/15
Y1 - 2014/8/15
N2 - The heat of hydrogenation of indenone was measured via two partially independent thermodynamic cycles by carrying out energetic measurements (i.e., electron affinities, proton affinities and ionization potentials) on both negative and positive ions (ΔH°H2 = 17.8 ± 5.5 and 17.5 ± 5.7 kcal mol-1, respectively). High level G3 computations were also carried out to provide the heats of formation of indenone (16.8 kcal mol-1) and cyclopentadienone (14.0 kcal mol -1). These 4n π electron systems are found to be nonaromatic in contrast to previous views. A recent report on cyclopropenyl anion (J. Org. Chem. 2013, 78, 7370-7372) indicates that this ion is also nonaromatic, and suggests that NMR ring currents and nucleus independent chemical shift (NICS) calculations do not correlate with the energetic criterion for antiaromatic compounds.
AB - The heat of hydrogenation of indenone was measured via two partially independent thermodynamic cycles by carrying out energetic measurements (i.e., electron affinities, proton affinities and ionization potentials) on both negative and positive ions (ΔH°H2 = 17.8 ± 5.5 and 17.5 ± 5.7 kcal mol-1, respectively). High level G3 computations were also carried out to provide the heats of formation of indenone (16.8 kcal mol-1) and cyclopentadienone (14.0 kcal mol -1). These 4n π electron systems are found to be nonaromatic in contrast to previous views. A recent report on cyclopropenyl anion (J. Org. Chem. 2013, 78, 7370-7372) indicates that this ion is also nonaromatic, and suggests that NMR ring currents and nucleus independent chemical shift (NICS) calculations do not correlate with the energetic criterion for antiaromatic compounds.
KW - Antiaromaticity
KW - Cyclopentadienone
KW - FTMS
KW - Heat of hydrogenation
KW - Indenone
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U2 - 10.1016/j.ijms.2014.06.011
DO - 10.1016/j.ijms.2014.06.011
M3 - Article
AN - SCOPUS:84903270265
SN - 1387-3806
VL - 369
SP - 87
EP - 91
JO - International Journal of Mass Spectrometry
JF - International Journal of Mass Spectrometry
ER -