Studies on the Chemistry of [Cd(NH3)4](MnO4)2. A Low Temperature Synthesis Route of the CdMn2O4+x Type NOx and CH3SH Sensor Precursors

. [Tetraamminecadmium(II)] bis(permanganate) (1) was prepared and its crystal structure was elucidated with XRD-Rietveld refinement and vibrational spectroscopic methods. Compound 1 has a cubic lattice consisting of a 3D hydrogen-bonded network built as four by four distorted tetrahedral blocks of [Cd(NH3)4]2+ cations and MnO4 anions, respectively. The other four permanganate ions are located in a crystallographically different environment, placed in the cavities formed by the attachment of the building blocks. A low-temperature (approximate to 100 degrees C) solid phase quasi-intramolecular redox reaction producing ammonium nitrate and amorphous CdMn2O4 could be established. Neither solid phase nor aqueous solution phase thermal deammoniation of compound 1 can be used to prepare Cd(MnO4)2 and [Cd(NH3)2(MnO4)2]. During deammoniation of compound 1 in aqueous solution a precipitate consisting of Cd(OH)2 forms. Additionally, solid MnO2 and ammonium permanganate (NH4MnO4) forms. The solid phase deammoniation reaction (toluene used as heat convecting medium) with subsequent aqueous leaching of the ammonium nitrate formed has proved to be an easy and convenient technique for the synthesis of amorphous CdMn2O4+x type NOx and MeSH sensor precursors. The 1-D perdeuterated complex was also synthesized to distinguish the NH(D) and OH(D) fragment signals in the TG-MS spectra and to elucidate the vibrational characteristics of the overlapping MnO and CdN frequencies.