Heterobimetallic thiocyanato-bridged coordination polymers based on [Hg(SCN)4]: Synthesis, crystal structure, magnetic properties and ESR studies

Three new M/Hg bimetallic thiocyanato-bridged coordination polymers; Hg(SCN)₄Ni(Im)₃]_∞1, Hg(SCN)₄Mn(Im)₂]_∞2, and Hg(SCN)₄Cu(Me-Im)₂ Hg(SCN)₄Cu(Me-Im)₄]_∞3, (Im=imidazole, Me-Im=N-methyl-imidazole), have been synthesized and characterized by means of elemental analysis, ESR, and single-crystal X-ray. X-ray diffraction analysis reveals that these three complexes all form 3D network structure, and their structures all contain a thiocyanato-bridged Hg?M?Hg chain (M=Mn, Ni, Cu) in which the metal and mercury centers exhibit different coordination environments. In complex 1, the Hg(SCN)₄]²⁻ anion connects three Ni(Im)₃]²⁺ using three SCN ligands giving rise to a 3D structure, and in complex 2, four SCN ligands bridge Hg(SCN)₄]²⁻ and Mn(Im)₂]²⁺ to form a 3D structure. The structure of 3 contains two copper atoms with distinct coordination environment; one is coordinated by four N-methyl-imidazole ligands and two axially elongated SCN groups, and another by four SCN groups (two elongated) and two N-methyl-imidazole ligands. The magnetic property of complex 1 has been investigated. The spin state structure in hetermetallic NiHgNi systems of complex 1 is irregular. The ESR spectra results of complex 3 demonstrate Cu²⁺ ion lie on octahedral environment.