Synthese und Struktur der basischen Erdalkalinitrate Sr2(OH)3NO3 und Ba2(OH)3NO3

Synthesis and Structure of the Basic Alkaline Earth Nitrates Sr₂(OH)₃NO₃ and Ba₂(OH)₃NO₃ Sr₂(OH)₃NO₃ and Ba₂(OH)₃NO₃ were synthesized from mixtures of freshly prepared strontium or barium hydroxides and their corresponding nitrates in evacuated quartz glass ampoules at 420 °C and 360 °C, respectively. Single crystals of Sr₂(OH)₃NO₃ were obtained in a solidified Sr(NO₃)₂ melt after subsequent heating and cooling cycles in air up to 600 °C. The crystal structure of the strontium compound was refined from single crystal and powder X‐ray data. Sr₂(OH)₃NO₃ crystallizes hexagonally in the space group (No. 189) with Z = 1 and the lattice parameters a = 6.624(2) Å and c = 3.560(1) Å (single crystal data). The powder pattern of Ba₂(OH)₃NO₃ was indexed isotypically to Sr₂(OH)₃NO₃ with the lattice parameters a = 6.9260(1) Å and c = 3.8086(1) Å, and the crystal structure was refined from powder X‐ray data. Alkaline earth ions in the structures are surrounded trigonal‐prismatically by six hydroxide ions. These prisms are sharing their trigonal faces along [001] building up columns. These columns are connected in the ab‐plane by shared edges, and form hexagonal tunnels with the nitrate groups stacked inside. Infrared and thermoanalytical data of Sr₂(OH)₃NO₃ are presented.