Complexes of carbon dioxide with dihalogenated ethylenes: structure, stability and interaction

摘要

Interactions of ethylene and its 1,2-dihalogenated derivatives with CO _(2) induce the formation of twenty four molecular complexes with stabilization energies in the range of 1.1 to 7.5 kJ mol ~(?1) as computed at the CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVDZ level. The stability of the parent C _(2) H _(4) ?CO _(2) complex is due to a π?π* interaction which has not yet been reported in the complexes of CO _(2) -philic compounds and CO _(2) . The cis -XCHCHX?CO _(2) complexes are found to be slightly more stable than the trans -XCHCHX?CO _(2) , with X = F, Cl and Br. Generally, the overall stabilization energy of each complex is determined by the C–H?O hydrogen bond and the C–X?C Lewis acid–base interaction, in which the latter plays a larger role. Substitution of two H atoms in CH _(2) CH _(2) by the same halogen atoms stabilizes the complexes XCHCHX?CO _(2) , and for the same dihalogenated derivatives, the stability of XCHCHX?CO _(2) tends to increase from X = F via Cl and to Br. The obtained results suggest that the contraction of the C–H bond involved in the C–H?O hydrogen bond and the blue-shift of its stretching frequency depend not only on a polarization of the C–H bond in the isolated monomer but also on the geometric shape of the complex formed.