An improved approach for predicting the density of azido compounds

Abstract

In this paper, a total of 30 azido compounds were optimised with the B3LYP method of density functional theory using six basis sets (3-21G, 6-31G, 6-31G*, 6-31G**, 6-31+G** and 6-311G*) and semi-empirical PM3 and AM1 methods. The molar volumes based on the isoelectron density contour were evaluated using a Monte Carlo integration scheme (model 1) and the integral equation formalism polarised continuum model (model 2). The densities were predicted subsequently. Excellent linear correlations were found between the results obtained with the two models, and different methods had little effect on the densities calculated using model 2. Quantitative relationships were established with the calculated and experimental densities of 25 azido compounds in the training set, and were used to predict the densities of five azido compounds in the testing set. The results obtained agree well with the experimental data, and model 2 gives a better result than model 1, with root mean square errors being 0.02 and 0.03 g cm^− 3, respectively. Therefore, model 2 is a more reliable and convenient model to predict the densities of azido compounds. This approach is believed to be applicable to other kinds of compounds too.

Keywords::

• azido compounds
• density
• DFT
• MC
• IEFPCM

Acknowledgements

We thank the Research Fund for the Doctoral Program of Higher Education of China (no. 20103219120014), the Special Foundation of China Postdoctoral Science Foundation (no. 201003588), the NUST Research Funding (no. 2011YBXM68) and the NUST ‘Excellent Plan and Zijin Star’ Research Foundation for their support.