Complexes between lithium cation and diphenylalkanes in the gas phase: The pincer effect

Gal J-F, Maria P-C, Mo O, Yanez M, Kuck D (2006)
CHEMISTRY-A EUROPEAN JOURNAL 12(29): 7676-7683.

Zeitschriftenaufsatz | Veröffentlicht | Englisch
 
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Abstract / Bemerkung
The gas-phase lithium cation basicities (LCB values, Gibbs free energies of binding) of a,omega-diphenylalkanes Ph-(CH2)(n)-Ph (n = 2, 3, or 7) and 1,1-diphenylethane Ph-CH(Me)-Ph were investigated by means of Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry. Their structures, and those of the corresponding Li+ complexes were optimized at the B3LYP/6-31G(d) level and their relative stabilities calculated at the B3LYP/6-31.1+G(3df,2p)//B3LYP/6-31G(d) level. Whereas the most stable conformers of the free diphenylalkanes were found to adopt a completely stretched aliphatic chain connecting the two benzene rings, the most stable Li+ complexes correspond to conformers in which the alkali metal cation interacts simultaneously with both benzene rings through the folding of the aliphatic chain ("pincer effect"). This chelation brings about a significant enhancement of the Li+ binding enthalpies (LBE values), which were calculated to be approximately 75 kJ mol(-1) higher than those evaluated for conventional (singly coordinated) pi complexes in which the metal cation interacts with only one of the benzene rings. The increase of the corresponding lithium cation basicities, however, (Gibbs free energies of Li+ binding, LCB values) was calculated to be smaller by approximately 15 kJ mol(-1) as the pincer effect is entropically disfavored. The good agreement between the calculated LCB values, assuming a statistical distribution of the different conformers present in the gas phase, and the experimental LCB values measured by means of FTICR mass spectrometry are considered indirect evidence of the existence of the pincer effect.
Stichworte
cation-pi interactions; ion cyclotron; resonance techniques; lithium; pincer effect; density functional calculations
Erscheinungsjahr
2006
Zeitschriftentitel
CHEMISTRY-A EUROPEAN JOURNAL
Band
12
Ausgabe
29
Seite(n)
7676-7683
ISSN
0947-6539
eISSN
1521-3765
Page URI
https://pub.uni-bielefeld.de/record/1597465

Zitieren

Gal J-F, Maria P-C, Mo O, Yanez M, Kuck D. Complexes between lithium cation and diphenylalkanes in the gas phase: The pincer effect. CHEMISTRY-A EUROPEAN JOURNAL. 2006;12(29):7676-7683.
Gal, J. - F., Maria, P. - C., Mo, O., Yanez, M., & Kuck, D. (2006). Complexes between lithium cation and diphenylalkanes in the gas phase: The pincer effect. CHEMISTRY-A EUROPEAN JOURNAL, 12(29), 7676-7683. doi:10.1002/chem.200501572
Gal, J. - F., Maria, P. - C., Mo, O., Yanez, M., and Kuck, D. (2006). Complexes between lithium cation and diphenylalkanes in the gas phase: The pincer effect. CHEMISTRY-A EUROPEAN JOURNAL 12, 7676-7683.
Gal, J.-F., et al., 2006. Complexes between lithium cation and diphenylalkanes in the gas phase: The pincer effect. CHEMISTRY-A EUROPEAN JOURNAL, 12(29), p 7676-7683.
J.-F. Gal, et al., “Complexes between lithium cation and diphenylalkanes in the gas phase: The pincer effect”, CHEMISTRY-A EUROPEAN JOURNAL, vol. 12, 2006, pp. 7676-7683.
Gal, J.-F., Maria, P.-C., Mo, O., Yanez, M., Kuck, D.: Complexes between lithium cation and diphenylalkanes in the gas phase: The pincer effect. CHEMISTRY-A EUROPEAN JOURNAL. 12, 7676-7683 (2006).
Gal, Jean-Francois, Maria, Pierre-Charles, Mo, Otilia, Yanez, Manuel, and Kuck, Dietmar. “Complexes between lithium cation and diphenylalkanes in the gas phase: The pincer effect”. CHEMISTRY-A EUROPEAN JOURNAL 12.29 (2006): 7676-7683.

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