Hydrogen bonds and halogen bonds in complexes of carbones L→C←L as electron donors to HF and ClF, for L = CO, N2, HNC, PH3, and SH2

Ab initioMP2/aug'-cc-pVTZ calculations have been carried out to determine the structures and binding energies of the carbone complexes in which the carbone L -> C <- L acts as an electron pair donor to one and two HF or ClF molecules, for L = CO, N-2, HNC, PH3, and SH2. The binding energies increase with respect to the ligand in the order CO < NN < CNH MUCH LESS-THAN PH3< SH2, and increase with respect to the acid in the order HF < 2 HF < ClF < 2 ClF. The complexes with the ligands CO, N(2)and PH(3)haveC(2v)symmetry while those with CNH and SH(2)haveC(s)symmetry, except for H2S -> C <- SH2:2HF which hasC(2)symmetry and a unique structure among all of the carbone complexes. F-H and Cl-F stretching frequencies in the complexes decrease as the F-H and Cl-F distances, respectively, increase. EOM-CCSD spin-spin coupling constants(2h)J(F-C) increase with decreasing F-C distance. Although the F-HMIDLINE HORIZONTAL ELLIPSISC hydrogen bonds gain some proton-shared character in the most tightly bound complexes, the hydrogen bonds remain traditional hydrogen bonds.(1x)J(Cl-C) values indicate that the ClMIDLINE HORIZONTAL ELLIPSISC halogen bonds have chlorine shared character even at the longest distances.(1x)J(Cl-C) then increases as the Cl-C distance decreases, and reaches a maximum for chlorine-shared halogen bonds. As the Cl-C distance further decreases, the halogen bond becomes a chlorine-transferred halogen bond.