Bismuth(III) salts with malonic acid: synthesis, structure and properties

The process of precipitation of bismuth(III) from perchloric acid solutions when malonic acid is added to them has been studied depending on the molar ratio of malonate ions to bismuth in the system. The basic bismuth malonate of the composition BiOH(C3H2O4) (compound I) and two identical in composition but different in structure bismuth malonates containing a water molecule were synthesized: Bi(C3H2O4)(C3H3O4)H2O (II) and [Bi(C3H2O4)(C3H3O4)] ∙ H2O (III). The basic bismuth malonate was obtained in X-ray amorphous form, and crystal structures were determined for the other two compounds by X-ray diffraction analysis. In compound II, a water molecule coordinates the bismuth and is a ligand, while in compound III it does not. Both compounds are one-dimensional (1D) coordination polymers. After calcination of compounds II and III at 120°C, anhydrous bismuth malonate of the composition Bi(C3H2O4)(C3H3O4) (IV) is formed by dehydration. All new compounds I–IV were characterized by IR spectroscopy, thermal analysis, powder diffractometry, and their compositions were confirmed by elemental analysis. The structure features of polymers II and III have been discussed, the topological analysis of the electron density of Bi–O contacts has been carried out, and the main and secondary bonds in coordination polyhedra have been identified.