Theoretical study of the inter-ionic and inter-molecular hydrogen bonds constructed by GZT, ZT 2− ions and their relative derivatives

Abstract

Diguanidinium 5,5′-azotetrazolate (GZT) is an ionic type high energy compound, which is combined with two guanidinium C(NH 2) 3 + (or simplified as G +) cations and one ZT 2− dianion. The structure of the ZT 2− is constructed using two N 4C tetrazole type five membered rings which are connected by an azo type (–N N–) linkage. A similar type of ‘inter-ionic hydrogen bonding type high energy compounds’ which were formed with various cations and ZT 2− have also been reported in the recent experimental paper. Within the limitations of quantum mechanical calculations, the combination of ZT 2− anions and cations with –NH 2 or with –OH groups have been selected for the theoretical study of this near planar sandwich type structure. With B3LYP/6-311+G(2d,p) and B3LYP/6-31G(d,p) density function theory (DFT) type SCF calculations, we found a set of varying types of inter-ionic or inter-molecular hydrogen bonding systems. When using the –NH 2 group in the cation, the inter-ionic system is the easily formed in most of the cases. But when substituting the –NH 2 with the –OH group in the cation, the hydrogen bonding system will be transformed into the inter-molecular type molecular combination of H 2ZT and formic acid molecules, or into the mixed inter-ionic and inter-molecular hydrogen bonding system of HZT − anion, formalmide molecule and some cations after the optimization procedures of the DFT type calculation. The stepwise type energy differential method found with bsse (basis-set superposition error) corrections and the various localized type analyses of H-bonding problems are processed together to determine H-bonding strengths. The order of localized H-bond strengths for each of the structures found with the differential method is arranged for all of the studied systems. The consistent results of the various methods are successfully obtained for the determination and comparison of localized H-bond strengths.