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RESEARCH PRODUCT

The preparation, IR spectrum and structure of the Di-μ3-hydroxo-μ-sulphatotetrakis-μ-(isonicotinato-N-oxide)tetraaqua-tetracopper(II)

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Abstract A very unusual new copper(II) complex with isonicotinate N-oxide (N-inicO), Cu4(N-inicO)4SO4(OH)2(H2O)4 has been prepared and its crystal and molecular structure determined from three dimensional X-ray diffraction data. The crystals belong to the monoclinic space group C2. The cell parameters are a = 19.089(8), b = 6.884(3), c = 19.533(12) A, β = 140.9(3)°, dobs = 1.99, dcalc = 2.01 and Z = 2. The structure was refined to a final R-value of 0.062. The monomeric tetranuclear complex resembles a space ship with the sulphate group at its top and pyridine rings as wings. Two copper atoms are very close to each other in the molecule; the Cu1Cu1′ distance is 2.885 A. The coordination around the all copper atoms is square pyramidal with a rather long axial coordination. Isonicotinate-N-oxide acts as a bridging ligand coordinating bidentately through both carboxylate O atoms and forming bridges between copper atoms Cu1 and Cu2. The N-oxide O atoms form hydrogen bonds with coordinated water molecules. Hydroxo groups form two three-fold bridges symmetrically between copper atoms Cu1, Cu1′ and Cu2, and the sulphate group forms a bridge between two copper atoms Cu1 and Cu1 . The sulphur of the sulphate group is situated at the special point of the space group.