Synthesis and crystal structure of two novel nickel (imidazole) complexes having hydrogen-bonded networks

Two nickel (imidazole) complexes, Ni(im)₆Cl₂· 4H₂O (1) and Ni(im)₆(NO₃)₂ (2) (im=imidazole) have been synthesized and characterized by elemental analysis, IR, UV, TG and single crystal X-ray diffraction. 1 crystallizes in the triclinic space group P-1 with a=8.800(6) Å, b=9.081(6) Å, c=10.565(7) Å, α=75.058(9)°, β=83.143(8)°, γ=61.722(8)°, V=718.3(8) ų, Z=1 and R₁ (wR₂)=0.0469 (0.1497). 2 crystallizes in the trigonal space group R-3 with a=12.370(6) Å, b=12.370(6) Å, c=14.782(14) Å, α=90.00°, β=90.00°, γ=120.00°, V=1959(2) ų, Z=3 and R₁ (wR₂)=0.0358 (0.0955). 1 and 2 exhibit different supramolecular network due to their different counter anions and different hydrogen bonding connection. In compound 1, [Ni(im)₆]²⁺ cation and counter anions Cl^- alternatively array in an ABAB fashion via N-H⋯Cl hydrogen bonding. In compound 2, the plane of each NO ₃^2- is almost parallel and each NO₃ ^2- connect three different [Ni(im)₆]²⁺ cations via N-H⋯O hydrogen bonding.