Diversity of Crystal Structures in a System Containing Complex Ions [Pt(NH₃)₄]²⁺ and [Rh(C₂O₄)₃]^3–

Numerous crystal products with different ratios of complex ions can be obtained by varying the conditions of double complex salts precipitation from aqueous solutions containing [Pt(NH₃)₄](NO₃)₂ and Na₃[Rh(C₂O₄)₃]. Since all these salts are crystal hydrates, the variety of obtained crystal structures is complemented by different contents of crystallization water molecules. The following complex compounds are obtained by the interaction of [Pt(NH₃)₄](NO₃)₂ and Na₃[Rh(C₂O₄)₃] in an aqueous solution: [Pt(NH₃)₄]₂[Rh(C₂O₄)₃](NO₃)·3H₂O (I), Na₄[Pt(NH₃)₄][Rh(C₂O₄)₃]₂7H₂O (II), Na₄[Pt(NH₃)₄][Rh (C₂O₄)₃]₂·6H₂O (III), Na[Pt(NH₃)₄][Rh(C₂O₄)₃]·4H₂O (IV), [Pt(NH₃)₄]₃[Rh(C₂O₄)₃]₂·6H₂O (V), Na[Pt(NH₃)₄][Rh(C₂O₄)₃]·3H₂O (VI), [Pt(NH₃)₄]₃[Rh(C₂O₄)₃]₂·5H₂O (VII). The crystals of the isolated compounds are characterized by single-crystal XRD, IR spectroscopy, powder XRD, and chemical analysis. Their thermal properties are studied, and their thermolysis products are determined.