The strengthening effect of a hydrogen or lithium bond on the Z•••N aerogen bond (Z = Ar, Kr and Xe): a comparative study

An ab initio study is performed on O(3)Z center dot center dot center dot NCM center dot center dot center dot NCX (Z=Ar, Kr and Xe; M=H and Li; X=H, F and CH 3) complexes to investigate cooperativity effects between aerogen and hydrogen or lithium bonding interactions in these systems. To understand the cooperative effects, a detailed analysis of the binding distances, interaction energies and bonding properties is performed on these complexes. The results indicate that all Z center dot center dot center dot N and H/Li center dot center dot center dot N binding distances in the ternary complexes are shorter than those of corresponding binary systems. For a given M or X, cooperative energies increase as Z = Xe > Kr > Ar. Moreover, O(3)Z center dot center dot center dot NCLi center dot center dot center dot NCX complexes exhibit a larger cooperative energy than O(3)Z center dot center dot center dot NCH center dot center dot center dot NCX ones. The non-covalent interaction (NCI) index analysis indicates that the formation of an H/Li center dot center dot center dot N interaction in the ternary complexes shifts the location of the spike associated with the Z center dot center dot center dot N interaction towards the negative lambda(2)rho values. This indicates that NCI analysis can be regarded as a useful tool for the study of cooperative effects between two different non-covalent interactions. Also, cooperative effects in O(3)Z center dot center dot center dot NCM center dot center dot center dot NCX complexes make a decrease in N-14 nuclear quadrupole coupling constants of NCH or NCLi molecule. [GRAPHICS] .