Thermal and FT-IR studies on the interaction between Cr(NO3)3·9H2O and some diols [articol]

Abstract

This paper presents a study regarding the interaction between Cr(NO3)3 and 1,2- propanediol, 1,3-propanediol and 1,4-butanediol, respectively. Previous studies on the reaction between metal nitrates and diols showed that the primary C-OH groups of diols are oxidized by NO3 - to –COO- . The resulted carboxylate anions coordinate to the metal ions forming complexes that can be used as precursors for nanocrystalline metal oxides. The evolution of the redox reaction between Cr(NO3)3 and the diols was studied by thermal analysis and by FT-IR spectrometry. The FT-IR spectra of the obtained reaction products have confirmed the formation of carboxylate coordination compounds of Cr(III) evidenced by υass(–COO- ) at ~1680 cm-1 and ~1560 cm-1 and υs (–COO- ) at ~ 1370 cm-1 . These compounds thermally decompose in the range 250-300°C leading to amorphous nonstoechiometric chromium oxide (Cr2O3+x) which turns into nanocrystalline Cr2O3 oxide above 400°C.