[NiEn3]CrO4: Structure, thermal properties, and pseudomorphism

Resumo

The crystal structure of [NiEn₃]CrO₄ (En is ethylendiamine), C₆H₂₄CrN₆NiO₄ is studied: a = 9.0408(5) Å, c = 9.7466(4) Å, V = 689.92(8) ų, space group P6₃/mmc, Z = 2, d_x = 1.704 g/cm³, Ni–N 2.133(9) Å, ∠N–Ni–N 82.4(5)°. The thermal properties are determined. When it is heated in a hydrogen atmosphere, a mixture of nanocrystalline Ni and Cr₂O₃ powders with coherent scattering regions of 59 nm and 90 nm respectively is formed. It is demonstrated that thermal decomposition products consist of pseudomorphic particles that inherit the sizes and shapes of initial [NiEn₃]CrO₄ single crystals.