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Synthesis, crystal structure and properties of the cyano-bridged heteropolynuclear [Cu(meso)]3[Co(CN)6]2•9.5H2O compound

The novel compound [Cu(meso)]3[Co(CN)6]2•9.5H2O was prepared and characterized structurally, magnetically and spectroscopically (UV-vis, FTIR and EPR). The crystal structure is result of the self-assembly of three [Cu(meso)]2+ and two [Co(CN)6]3- units leading to a polymeric zigzag chain. Isolated [Cu(meso)(H2O)2]2+ units counterbalance the charge of the whole structure. The crystal packing shows a large hollow space in the structure and a significant number of water molecules are found in these cavities. Magnetic properties exhibited a very weak antiferromagnetic exchange interaction between the copper ions, with J = -0.3 cm-1. FTIR spectrum showed typical frequencies of n(O-H) at 3604 cm-1 and bridging and non-bridging n(CN) at 2184 and 2128 cm-1, respectively. The electronic spectrum of the title complex presented a broad and symmetric band at 547 nm, assigned to the overlaid z² → x²-y², xy → x²-y² and (xz, yz) → x²-y² transitions. EPR data at 77 K presented a typical axial spectrum with g// = 2.33 and g⊥ = 2.01, in accordance with the tetragonal distortion of the copper(II) ion as supported by the single-crystal X ray diffraction data.

polynuclear; cyano-bridge; single crystal X-ray diffractometry; antiferromagnetism


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