A 19F NMR study of C–I⋯π halogen bonding

Abstract

The formation of halogen bonded complexes between toluene-d 8 and the perfluoroiodopropanes 1-C 3F 7I and 2-C 3F 7I has been investigated using 19F NMR spectroscopy. For both Lewis acids, evidence was found for the formation of a C–I⋯π halogen bonded complex. The complex formed is a 1:1 type. Using spectra recorded at different temperatures, the complexation enthalpies and entropies for the complexes were determined to be −2.9(1) kJ mol −1 and −19.1(2) J K −1 mol −1 for the 2-C 3F 7I⋅toluene-d 8 complex and −2.7(1) kJ mol −1 and −16.0(4) K −1 mol −1 for the 1-C 3F 7I⋅toluene-d 8 complex. The experimental results are supported by ab initio calculations at the B3LYP-PCM/6-311++G(d,p) + LanL2DZ ∗ level.