engleski

Pseudopolymorphism with the two crystal series of the composition [M(bpy)_3]_2[NbO(C_2O_4)_3]Cl&middot ; ; ; nH_2O

As the first step in our efforts to synthesize polynuclear molecule-based magnetic compounds, we have isolated the new isostructural series of solids [M(bpy)_3]Cl_2[NbO(C_2O_4)_3]Cl&middot ; ; ; 11H_2O (M=Fe^2+, Co^2+, Ni^2+, Zn^2+) formed from aqueous solutions of [M(bpy)_3]Cl_2 and M'_3[NbO(C_2O_4)_3&middot ; ; ; nH_2O (M'=NH_4^+, alkali metal). All compounds crystallize as needle-like monoclinic crystals, space group P2_1/c. This crystal form is metastable and slowly (2-4 weeks) transforms into more stable polyhedra-like orthorombic crystals of the composition [M(bpy)_3]Cl_2[NbO(C_2O_4)_3]Cl&middot ; ; ; 12H_2O, space group P2_12_12_1). Methods used. IR spectroscopy, powder and single-crystal X-ray diffraction, magnetic susceptibility measurements. The crystal structures have been solved for all compounds and pseudopolymorphism found within pairs of complexes from the two series. Magnetic susceptibility measurements show no difference in magnetic behaviour of two pseudopolymorphs.

Pseudopolymorphism; Crystal structure; Polynuclear oxalato complexes; 2; 2'-bipyridine

nije evidentirano