J. Gal, P. Maria, M. Decouzon
Sep 1, 2002
Citations
0
Influential Citations
40
Citations
Journal
International Journal of Mass Spectrometry
Abstract
Abstract The gas-phase lithium-cation basicities of a series of monosubstituted benzene derivatives, namely C 6 H 5 X (X=H, Me, CHCH 2 , OH, OMe, SH, Cl, Br) have been measured by means of Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The structures of the corresponding complexes and their relative stabilities were investigated with B3LYP/6-311+G(3df,2p)//B3LYP/6-31G(d) density functional theory calculations. In all cases, the π-complexes are favored with respect to those in which the metal monocation interacts with the substituent. These latter kind of complexes, which are entropically favored with respect to the π-complexes, are found to be chelated species, in which Li + bridges the heteroatom of the substituent and the ipso carbon atom. The Li + basicity of the benzene derivatives investigated reflects the electron-donor ability of the aromatic moiety as a function of the substituent. Consistently, there is a linear correlation between the Li + basicity and the frequency of the vertical displacement of Li + with respect to the aromatic ring.