The synthesis, structure and magnetic properties of two cobalt phosphonate salts

• Published in: Polyhedron Vol. 81; pp. 132 - 141
• Main Authors: Garczarek, Piotr, Janczak, Jan, Duczmal, Marek, Zoń, Jerzy
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-10-2014
• Subjects: Cobalt(II) phosphonate salts; Crystal structure; Hydrogen bond; Magnetic properties; Supramolecular network; Cobalt(II) phosphonate salts; Supramolecular network; Crystal structure; Hydrogen bond; Magnetic properties
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2014.05.047

Synthesis and structure of two new metal phosphonate salts, as well as their IR spectra and magnetic properties are presented. Both compounds form a three-dimensional supramolecular network held together by a number of hydrogen bonds and show paramagnetic behaviour with very weak antiferromagnetic interactions through H-bonds. [Display omitted]
Two new cobalt(II) phosphonate salts, {3[Co(H2O)6]2(C12H18O9P3)}·11H2O (1) and {[Co(H2O)6](C12H19O9P3)}·6H2O (2), were obtained in crystalline form. Compound 1 crystallises in the centrosymmetric space group of the triclinic system, whereas compound 2 crystallises in the P21/n space group of the monoclinic system. The asymmetric unit of 1 consists of one and a half hexaaqua cobalt(II) ions, one phosphonic acid residue and five and a half lattice water molecules. One Co2+ ion lies in a special position and the other one in a general position. In 1, both independent Co2+ cations are surrounded by water molecules forming distorted octahedral coordination geometry. The asymmetric unit of 2 consists of one hexaaqua cobalt(II) ion, phosphonic acid residue and six lattice water molecules. In crystal 2, similarly as in crystal 1, the environment of the Co2+ consists of water molecules that form distorted octahedral coordination geometry. The hexaaqua cobalt(II) cations interact with phosphonate counter ions and together with the solvated water molecules they form a three-dimensional hydrogen bonding supramolecular network. Magnetic susceptibility measurements exhibit paramagnetic behaviour with very weak antiferromagnetic interactions for both compounds.