Crystal structure and thermal decomposition mechanism of [K(DNP)(H ₂O)_0.5]n

The new coordination polymer, [K(DNP)(H₂O)_0.5] _n(DNP=2,4-dinitrophenol) was prepared by the reaction of 2,4-dinitrophenol with potassium hydroxide. The molecular structure was determined by X-ray single-crystal diffraction analysis, FT-IR techniques, and elemental analysis. The crystal is monoclinic, space group C(2)/c with the empirical formula of C₆H₄N₂O_5.5K, M_r=231.21. The unit cell parameters are as follows: a=2.0789(3) nm, b= 1.2311(2) nm, c=0.7203(1) nm, β=109.611(15)°, V=1.7366(4) nm ³, Z=4, D_c=1.769 g/cm³, F(000)=936, μ (Mo Kα) =0.617 mm^-1. The potassium ions coordinate with all the oxygen atoms of phenolic hydroxyl group and nitro-group of different 2,4-dinitrophenol (DNP) ligands with high coordination number, and form a good cross-linked three-dimensional net structure of which makes the complex with good stabilities. The thermal decomposition of [K(DNP)(H₂O) _0.5]_n has only an intense exothermic process in the temperature range of 338-343°C corresponding to a mass loss of 75.02%. The final decomposition residue is potassium isocyanide.