Spectroscopic, Structural and Thermal Properties of Three New Metal Nitrates Templated by DABCO: (C6H14N2)[MII(H2O)6](NO3)4 with MII: Mn, Ni and Zn

Three new metal nitrates templated by 1,4-diazabicyclo[2.2.2]octane (DABCO) were successfully synthesized by slow evaporation method from aqueous solutions. Single crystals were characterized by X-ray diffraction technique which shows that all compounds crystallize in the monoclinic system, space group P21/c, with the following formula: (C6H14N2)[MII(H2O)6](NO3)4 with MII: Mn (Z = 8), Ni and Zn (Z = 4). The crystal structures of the three materials can be described as mixed organic and inorganic free entities linked together via N–H⋯O and OW–H⋯O hydrogen bonds. Although the three compounds present the same formula and adopt the same crystal system and space group they show different atomic arrangement and two structure types are distinguished. Indeed, the arrangement of the different entities along cationic and anionic layers makes the structure of the manganese compound different with respect to the two others which are isostructural. The thermal decomposition of the precursors proceeds through several steps. The first one consists in the dehydration which takes place in two stages and leads to intermediate anhydrous phases while the second corresponds to the total degradation ending with the formation of the metal oxides M2+O.