THE CRYSTAL-STRUCTURE OF TUTTONS SALT-TYPE K-2[CO(H2O)(6)](SO4)(2) - A COMBINED X-RAY AND NEUTRON STUDY

The crystal structure of dipotassium hexaaquacobalt(II) sulfate, K-2[C O(H2O)(6)](SO4)(2), has been determined at room temperature by single crystal X-ray diffraction. The deep purple crystals grown from aqueous solution are monoclinic, space group P2(1)/a, with unit cell dimensio ns a = 9.057(1) Angstrom, b = 12.211(2) Angstrom, c = 6.155(1) Angstro m, beta = 104.82(1)degrees, Z = 2, D-c = 2.207 Mg/m(3). The hydrogen a tom positions were obtained from a Rietveld refinement on neutron powd er data measured on a deuterated sample. Fixing these positions in the X-ray structure refinement on 1162 unique reflections (I > 2 sigma) r esulted in R(F) = 0.0188, wR(F-2) = 0.0504, GOF = 1.14. All structural details compare well with corresponding results reported for other me mbers of the Tut ton's salts series.