Preparation and characterization of tetrachlorocobaltates(II) of α,ω-alkylenediammonium. Magnetic and thermal properties. Crystal structure of [NH3(CH2)5NH3]CoCl4

Abstract

Tetrachlorocobaltates(II) of diprotonated α,ω-diaminoalkanes with the formula [NH3(CH2) n NH3]CoCl4, where n = 5 (cadaverine; 1,5-pentanediammonium tetrachlorocobaltate), 8 (1,8-octanediammonium tetrachlorocobaltate) and 10 (1,10-decanediammonium tetrachlorocobaltate), were prepared. The compounds were studied by mass spectrometry, FT-IR and visible spectroscopy, magnetic susceptibility techniques and thermal analysis. The compounds contain the tetrahedral tetrachlorocobaltate(II) ion and the corresponding diprotonated diamine (cadaverine, 1,8-octamethylenediamine and 1,10-decamethylenediamine). The compound corresponding to cadaverine crystallizes in the monoclinic space group P21/c, with lattice parameters a = 7.1633 (7), b = 15.940 (3), c = 11.137 (2) Å, β = 98.44 (1)° and Z = 4. Its crystal structure contains slightly distorted tetrahedral CoCl_4^{2-} ions: the largest difference in Co—Cl bond lengths is 0.029 Å and the largest difference in Cl—Co—Cl angles is 7.76°. The compound also contains diprotonated cadaverine ions. An extensive hydrogen-bonding network connects these ions. The slightly positive deviations of the magnetic susceptibility from the Curie–Weiss law are in agreement with the 4 A 2 ground state for the tetrachlorocobaltate anion. The compounds with eight and ten C atoms show phase transitions in the solid state and a greater complexity is observed in their differential scanning calorimetry curves. Unfortunately, no suitable single crystals of these could be obtained.