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Kristallstruktur zweier Zinkthiocyanat-Hexamethylentetramin-Addukte, Zn(SCN)2 · (C6H12N4)2 und {Zn(SCN)2 · C6H12N4 · 2H2O}n, mit unterschiedlich koordinierten Zinkionen

Pickardt, Joachim; Gong, Gill-Taik; Wischnack, Sabine; Steinkopff, Christina

Inst. Chemie

Crystals of the adducts Zn(SCN)2 · (C6H12N4)2 (1), and {Zn(SCN)2 · C6H12N4 · 2H2O}n (2) were obtained by crystallization from aqueous solutions containing hexamethylenetetrami­ne, potassium thiocyanate and zinc nitrate or zinc sulfate, resp., under identical conditions, as two totally different products. 1 crystallizes orthorhombically, space group P nmm, Z = 2, a = 622.4(5), b = 1152.3(7), c = 1394.0(9) pm; 2 is monoclinic, space group C2/c, a = 984.4(3), b = 1217.0(5), c = 1257.4(6) pm, and β = 111.69(5)°. The crystal structure of 1 contains discrete molecules of the complex, in which the zinc ion is tetrahedrally coordinated by two NCS ligands, and two hexamethylenetetramine molecules, which act as monodentate ligands. In 2 however, the zinc ions are octahedrally coordinated. A “supramolecular” structure is form­ed: The hexamethylenetetramine molecules act as bridging bidentate ligands and connect [Zn(H2O)2(NCS)2] units forming zig-zag chains. Adjacent chains are interconnected via hydrogen bonds. The formation of the two compounds with different coordination may be due to the fact, that the educts Zn(NO3)2 · 4H2O and ZnSO4 · 7H2O contain Zn(H2O)4 and Zn(H2O)6 moieties, resp., and that these species are retained in solution.