Theoretical investigation of the effect of O⋯M={Ti,Zr,Hf} interactions on the sensitivity of energetic N-nitro compounds

This paper outlines the role of intermolecular interactions involving group 4 transition metals in stabilising the N–NO₂ trigger bonds. Minimising sensitivity is the foremost priority in designing energetic compounds. A quantitative analysis with Molecular Electrostatic Potential (MEP) evidenced anomalies arising from the marked depletion of negative charge distribution of RDX and HMX. The Energy Decomposition Analysis with Natural Orbitals for Chemical Valence (EDA-NOCV) results reveal that the electrostatic and orbital contributions are the dominant factors driving the assembly of the M={Ti,Zr,Hf}-based complexes. Sensitivity of the N–NO₂ trigger bonds is investigated by using the Quantum Theory of Atoms in Molecules (QTAIM). The QTAIM topological analysis showed that the O⋯M={Ti,Zr,Hf} interaction strengthens these trigger bonds, revealing an increased stability to decomposition. This effect is more marked in the Hf- and Zr-based complexes. Finally, the results based on Interaction Indicator Region (IRI) are fully consistent with those generated from QTAIM analysis.