TY  - JOUR
AU  - Wallace, W.E.
AU  - Lewandowski, H.
AU  - Meier, R.J.
TI  - Reactive MALDI mass spectrometry of saturated hydrocarbons: A theoretical study
JO  - International journal of mass spectrometry
VL  - 292
SN  - 1387-3806
CY  - [S.l.]
PB  - Elsevier Science
M1  - PreJuSER-11775
PY  - 2010
N1  - Record converted from VDB: 12.11.2012
AB  - Recently it has been shown that the cobaltocenium cation, prepared by the laser ablation of a CoCp(CO)(2)/fullerene matrix, may react with alkanes and polyethylenes in the gas phase via a dehydrogenation reaction to produce [Co(Cp)(2)(alkadiene)](+) ions without chain scission (W.E. Wallace, Chem. Commun. 2007, 4525-4527). To better understand these experimental observations, density functional calculations were used to obtain the gas phase binding energies and molecular structures of cobaltocenium, Co(Cp)(2)(+), with 1,3-butadiene, 2,4-hexadiene, and 2,3-hexadiene. Calculations were conducted for both cis and trans molecular configurations, in both singlet and triplet electronic states, and with a variety of cyclopentadienyl hapticities. For 1,3-butadiene the 18-electron rule would predict a [Co(eta(5)-Cp)(2)(1,3-butadiene)](+), however, the lowest energy structure, [Co(eta(5)-Cp)(2)(1,3-butadiene)](+), has a higher than expected cyclopentadienyl hapticity. In this structure a distance of nearly 0.5 nm between the metal core and the butadiene ligand leads to very little electron sharing. Thus the detected ions are better described as non-covalent ion-molecule complexes. In turn, the lack of orbital overlap leads to a low enthalpy giving the cis-butadiene complex a -13.0 kJ/mol binding energy and the trans-butadiene binding a -3.8 kJ/mol binding energy. These low binding energies lead to low levels of charged alkanes in the reactive ion formation process in agreement with experimental observations. Published by Elsevier B.V.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000277854900005
DO  - DOI:10.1016/j.ijms.2010.02.012
UR  - https://juser.fz-juelich.de/record/11775
ER  -