tris-Ethylenediamine Complexes of Rhodium(III) and Iridium(III): Synthesis, Crystal Structures, and Formation of Double Complex Salts with Oxalato Cuprate(II)

Optimal synthesis procedures with the use of the hydrothermal approach and providing high yields are developed for complex salts M(en)3X3·nH2O (M = Rh, Ir; X = Cl, I), and new double complex salts (DCSs) with oxalato cuprate(II) are also obtained. M(en)3I3·H2O (M = Rh, Ir) and M(en)32Cu(H2O)(C2O4)22Cu(H2O)2(C2O4)2·nH2O (M = Rh, Ir) DCSs are structurally characterized for the first time. These compounds are isostructural to similar cobalt salts. The crystal structures of Ir(en)3Cl3·0.25KCl·3.25H2O, Rh(en)3Cl3·0.5KCl·3H2O, and Ir(en)3Cu(H2O)2(C2O4)20.5CuI2 (C2O4)20.5·5H2O salts are determined. Thermal destruction processes of DCSs are studied in detail in reducing and inert atmospheres. Thermal decomposition of the compounds is shown to lead to the formation of stable and metastable MxCu1–x (M = Rh, Ir) solid solutions.