Association of copper(II) isonicotinamide moieties via different anionic bridging ligands: Two paths of ferromagnetic interaction in the azide coordination compound |
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| Authors: | Marijana ?akovi? Zvonko Jagli?i? Bojan Kozlev?ar Zora Popovi? |
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| Institution: | 1. Laboratory of General and Inorganic Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia;2. Institute of Mathematics, Physics and Mechanics and Faculty of Civil and Geodetic Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia;3. Faculty of Chemistry and Chemical Technology, University of Ljubljana, A?ker?eva 5, SI-1000 Ljubljana, Slovenia |
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| Abstract: | Three isonicotinamide (isn) copper(II) complexes with different bridging ligands, azide, thiocyanate and sulfate, have been prepared. The molecular structure of Cu2(μ-1,1-N3)2(μ-1,3-N3)2(isn)2]n (1) is composed of binuclear species, Cu2(μ-1,1-N3)2(isn)2, inter-connected by additional four azide bridges in the end-to-end mode (1,3). This gives a CuN4N square-pyramidal coordination sphere around each copper(II) ion. A trans mononuclear octahedral coordination sphere CuN4S2 is present in Cu(μ-N,S-NCS)2(isn)2]n (2), with thiocyanato ligands serving as bridges between the adjacent Cu(isn)2 moieties. The third anionic ligand, i.e. sulfate, in {Cu(μ-O,O’-SO4)(H2O)(isn)2]·2H2O}n (3) completes the CuO2N2O square-pyramidal coordination sphere, and thus enables bridging between the mononuclear Cu(H2O)(isn)2 moieties. The ligands that bridge the principal building blocks, i.e. binuclear in 1 and mononuclear in 2 and 3, connect the axial ligands with the equatorial positions of the copper(II) coordination spheres in all three cases. A ferromagnetic interaction FM is found for 1, while 2 and 3 are paramagnetic. Therefore, the key structural difference between 1 on one hand, and 2 and 3 on the other, is found in the anionic ligand, serving in 1 also as the intra-binuclear bridge, showing the main path (J1) for the FM interaction. Additionally, the inter-binuclear pathway in 1 gives another contribution (J2) to the whole FM interaction seen herein (J1 = 18.5 cm–1, J2 = 4.9 cm–1). |
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