6533b85efe1ef96bd12c0544

RESEARCH PRODUCT

The structure of polymeric diaquo-di-μ-hydroxo-bis-μ-(nicotinato-N-oxide)-bis-μ-(nicotinato-N-oxide)tricopper(II)

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Abstract The new unusual polymeric copper(II) complex with nicotinate N-oxide (N-nicO), [Cu3(N-nicO)4(OH)2(H2O)2]n was prepared and its crystal and molecular structure was determined from three-dimensional X-ray diffraction data. The crystals belong to the triclinic space group P 1 (No. 2). The cell parameters are a = 7.881(9), b = 9.658(11), c = 10.368(12) A, α = 97.32(9), β = 110.38(9), γ = 109.53(9)°, V = 670(1) A3, dobs = 1.94 (dcalc = 2.02) and Z = 1. The structure was refined to a final R-value of 4.13%. The complex is a polymeric, linear chain along the c-axis, and its structure units are connected with each other through two N-oxide oxygen atoms. There are three copper atoms (Cu1, Cu2, Cu2′) that are very close to each other in the structure unit, and the CuCu distances are 3.035 A. The coordination around the copper atom Cu1 is square planar and around the copper atoms Cu2 and Cu2′ it is square pyramidal with long axial coordination. Nicotinate-N-oxide acts as a bridging ligand and is coordinated bidentately either through both carboxylate O atoms forming a bridge between Cu1 and Cu2 (Cu2′) or through one carboxylate O atom and the N-oxide O atom forming a double bridge between Cu2 and Cu2′ in separate structural units. Water molecules are coordinated with copper atoms Cu2 and Cu2′, and hydroxide groups form a bridge between Cu1 and Cu2, both Cu1 and Cu2′, respectively.