Crystallization and characterization of the compounds Gly·MSO 4 · m H 2 O (M=Mg 2+ , Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , Zn 2+ ; m =0, 3, 5, 6)

The equilibrium crystallization of complex compounds of the type Gly center dot MSO4 center dot 5H(2)O with a structure derived from those of the crystallized double salts MSO4 center dot xH(2)O, where x = 6, 7 was predicted and proven in the systems Gly-MSO4-H2O (M = Mg2+, Mn2+, Fe2+, Co2+, Ni2+ and Zn2+). It was predicted that stable octahedral complexes [M(H2O)(6)](2+) and trans-[M(H2O)(4)(O-gly)(2)](2+), as well as [SO4](2-) tetrahedra, which were the main building units of the crystallizing Gly center dot MSO4 center dot 5H(2)O compounds (triclinic crystal system, space group P - 1), were predominating in these solutions. The vibrational spectra and the thermal behavior of the Gly center dot MSO4 center dot 5H(2)O compounds (M = Mg2+, Co2+, Zn2+) are in accord with the refined crystal structures. The cobalt compound displays antiferromagnetic behavior whereas the nickel and manganese compounds are ferromagnetic. In the manganese system where MnSO4 center dot H2O (308 K) crystallizes, the only complex compound is the anhydrous Gly center dot MnSO4 with a polymeric type structure (trans-[Mn(SO4)(4)(O-gly)(2)](n)(2-)). A new compound Gly center dot CoSO4 center dot 3H(2)O was found in the cobalt system under unstable equilibrium conditions. Gly center dot CoSO4 center dot 3H(2)O was proven to consist of two types of octahedra, trans-[Co(H2O)(4)(O-gly)(2))(2+) and trans-[Co(H2O)(2)(SO4)(2)(O-gly)(2)](2-), forming a chain structure (monoclinic crystal system, space group P2(1)/c). (C) 2012 Elsevier B.V. All rights reserved.