Arsenic(III) oxide intercalate with ammonium chloride: crystal structure revision and thermal characterization

According to the crystal structure determination by Edstrand& Blomqvist [Ark. Kemi (1955), 8, 245 – 256], intercalate NH4Cl · As2O3 · 0.5H2O ({\bf Y_{{NH}_{4}Cl}}) is not isostructural with compound KCl · As2O3 · 0.5H2O. This is very unlikely because both NH4Br · 2As2O3 and KBr · 2As2O3 as well as NH4I · 2As2O3 and KI · 2As2O3 are isostructural. Hence, intercalate {\bf Y_{{NH}_{4}Cl}} has been studied using single-crystal X-ray diffraction in addition to attenuated total reflection Fourier transform infrared (ATR-FTIR) and 15N solid-state magic-angle spinning nuclear magnetic resonance (ssNMR) spectroscopies. These techniques indicate that revising the previous crystal structure model is necessary. Compound {\bf Y_{{NH}_{4}Cl}} crystallizes in space group P6/mmm with unit-cell parameters a = 5.25420   (10)   Ã… and c = 12.6308   (3)   Ã… and is isostructural with KCl · As2O3 · 0.5H2O. The presence of two symmetry-independent ammonium cations in the structure has been unequivocally confirmed using 15N ssNMR spectroscopy. The 15N ssNMR spectrum of intercalate {\bf Y_{{NH}_{4}Cl}} has been compared with analogous spectra of NH4Br · 2As2O3 and NH4I · 2As2O3 which allowed for a probable assignment of signals to ammonium cations occupying particular sites in the crystal structures. Thermogravimetry, differential scanning calorimetry and variable-temperature ATR-FTIR spectra have revealed that intercalate {\bf Y_{{NH}_{4}Cl}} is dehydrated between 320 and 475 â...

Source: Acta Crystallographica Section B - April 18, 2023 Category: Chemistry Authors: Wrze Å› niewska, W. Paluch, P. Gu Å„ ka, P.A. Tags: arsenic(III) oxide intercalates solid-state NMR crystal structure research papers Source Type: research