Syntheses, crystal structures, and magnetic properties of two isostructural complexes (trenH4)2[CoX4]X6 (X = Cl, Br)

Two novel complexes (trenH 4 ) 2 [CoCl 4 ]Cl 6 and (trenH 4 ) 2 [CoBr 4 ]Br 6 (tren = tris(2-aminoethyl)amine) were isolated in the form of single crystals from the aqueous systems CoX 2 —tren—HX (X = Cl, Br). The chemical composition of formed complexes was corroborated by chemical analysis and IR spectroscopy. The crystal structures of isostructural compounds are ionic and are built up of tetrahedral anions [CoX 4 ] 2− , additional halogenido anions X − , and tetraprotonated (trenH 4 ) 4+ organic cations. The organic cations and complex anions are also connected beside ionic forces by hydrogen bonding interactions of the N–H···X type. The temperature variable magnetic studies (2–300 K) confirm the paramagnetic behavior of both complexes with zero-field splitting parameter D governing the magnetic behavior below 30 K. The fitting procedures yielded for D / hc values of +10.5 and +13.8 cm −1 for the chlorido and the bromido complex, respectively. Graphical Abstract .