[NH_3(CH_2)_2NH_3][Co(SO_4)_2(H_2O)_4]: Chemical preparation, crystal structure, thermal decomposition and magnetic properties

摘要

Cobalt ethylenediammonium bis(sulfate) tetrahydrate, [NH_3(CH_2)_2NH_3][Co(SO_4)_2(H_2O)_4], has been synthesised by slow evaporation at room temperature. It crystallises in the triclinic system, space group PI, with the unit cell parameters: a = 6.8033(2), b = 7.0705(2), c = 7.2192(3) A, α = 74.909(2)°, β = 72.291(2)°, γ = 79.167(2)°, Z = 1 and V = 317.16(2) A~3. The Co(11) atom is octahedrally coordinated by four water molecules and two sulfate tetrahedra leading to trimeric units [Co(SO_4)_2(H_2O)_4]. These units are linked to each other and to the ethylenediammonium cations through OW-H.. .O and N-H.. .0 hydrogen bonds, respectively. The zero-dimensional structure is described as an alternation between cationic and anionic layers along the crystallographic b-axis. The dehydration of the precursor proceeds through three stages leading to crystalline intermediary hydrate phases and an anhydrous compound. The magnetic measurements show that the title compound is predominantly paramagnetic with weak antiferromagnetic interactions.