Could the lithium bond be classified as the σ-hole bond? - QTAIM and NBO analysis

The lithium bond is analyzed in complexes of ZH(3)Li and ZF(3)Li (Z=C, Si and Ge) acting as the Lewis acids with HCN and N-2 Lewis bases. There are the unique properties of the lithium bond if it is compared with the other non-covalent interactions. For the lithium bond the complexation leads to the decrease of the positive charge of the Li-atom and the increase of its volume while for the hydrogen bond usually the increase of the positive charge of H-atom and the decrease of its volume is observed. The lithium bond may be probably classified as the sigma-hole bond. The other properties of the lithium bond are presented and analyzed based on MP2/aug-cc-pVTZ calculations, the quantum theory of atoms in molecules, natural bond orbitals method and the decomposition of the interaction energy. (C) 2013 Elsevier B.V. All rights reserved.