Microsolvation of lithium iodide dimer studied by ab initio calculations

Abstract

The structures of microsolvated (LiI)2−(H2O)n (n=0–6) clusters and their corresponding neutrals were determined using ab initio calculations. One Li-I distance in (LiI)2−(H2O)n abruptly increases at n=5, thus a I atom is firstly seperated out from the (LiI)2− unit. For the neutrals, the notable elongation of Li-I distances occurs at n=4, and a I atom prefer to leave the (LiI)2 unit. The charge analyses show that the excess electrons mainly localizes on the terminal Li atom for (LiI)2−(H2O)0-1, whereas charge transfer to water occurs when the number of water reaches 2. The RDG analyses show that Li+-water interactions are dominant, and with the increase of water molecules, the I−-water and water-water interactions are considerably enhanced. The comparison of (LiI)2−(H2O)n and (MI)2−(H2O)n (M=Na, K) indicates that (LiI)2− is more difficult to be pried apart than (MI)2−.