Crystal structure, thermal decomposition mechanism and explosive properties of [Na(H₂TNPG)(H₂O)₂]_n

The new coordination polymer of sodium trinitrophloroglucinate, [Na(H ₂TNPG)(H₂O)₂]_n, was synthesized by reacting trinitrophloroglucinol (H₃TNPG) with NaHCO₃ in aqueous solution and [Na(H₂TNPG)(H₂O)₂] _n was recrystallized to be yellow single crystal. The title compound was characterized by using elemental analysis and Fourier transform infrared (FT-IR) spectrum. Its crystal structure was determined by single crystal X-ray diffraction analysis. The crystalline belongs to monoclinic system and C2/c space group. Each Na⁺ ion is six-coordinated to one H ₂TNPG^- anion and four water molecules in which the oxygen atoms in the water molecules act as bridging atoms. Coordination bonds, electrostatic interaction and intermolecular hydrogen bonds assemble the ions into network structures. The thermal decomposition mechanism of the complex was studied by using differential scanning calorimetry (DSC), thermogravimetry/ derivative thermogravimetry (TG/DTG) and FT-IR techniques. Under nitrogen atmosphere with a heating rate of 10°C/min the thermal decomposition of the complex contained one endothermic and five exothermic processes. Two intense exothermic decomposition processes were observed in the range of 173-228°C suggesting its energetic nature and the solid decomposition residue at 500°C was sodium isonitrile. Explosive properties revealed that the compound is sensitive to mechanical stimuli. All properties data observed show that the title compound has explosive properties and can act as components of ecologically clean initiating compositions.