engleski

Different architectures of oxalate‐ and chloranilate‐bridged heterometallic compounds with 1, 10'‐phenanthroline

Chemically bonded organic and inorganic hybrid materials, i.e., metal coordination compounds, are a major current research area, which involves their design, synthesis, and potential applications. The adaptable nature of the organic ligands and their variety of coordination modes, together with the geometry of the constitutive metal ions, provide an assortment of topologies and different architectures that can be accomplished by chemical design. In the field of molecular magnetism, coordination polymers have been extensively used to generate molecule-based magnetic materials exhibiting spontaneous magnetization above room temperature, or at least above liquid nitrogen. Oxalate ion, C2O42−, has an important role in design and synthesis of the heteropolynuclear complexes due to its various possibilities of coordination to metal centers and its ability to mediate magnetic interactions between paramagnetic metal ions. For the preparation of extended multifunctional systems stable mononuclear anionic oxalate complexes as tris(oxalato)metalate anions, [MIII(C2O4)3]3− (MIII = Mn, Cr, Fe, V), are often used as ligands toward another metal ion. Magnetic properties of oxalate-based compounds can be tuned by acting directly on the exchange pathways within the chains/layers by varying metal centres or modifying the bridging oxalate ligand, as using larger bis(bidentate) bridging ligands, for example dianion of 2, 5-dihydroxy-1, 4-benzoquinone (H2dhbq) and its derivatives (C6O4X22− = X2An2−). Applying the layering technique and using K3[M(C2O4)3]·3H2O (M = Cr3+, Fe3+) or [(n-Bu)4N]3[Cr(Cl2An)3] as building blocks in reactions with CuCl2·H2O and 1, 10'-phenanthroline, the single crystals of heteropolynuclear complexes 1─3 have been formed. Structures of green prismatic crystals of compounds {; ; ; ; [Cu3(phen)3(H2O)Cr(C2O4)4][Cu(phen)Cr(C2O4)3] ·3H2O·CH3CN}; ; ; ; n (1) and {; ; ; ; [Cu4(phen)4Fe2(C2O4)7]·3H2O·3CH2Cl2}; ; ; ; n (2) consist of one-dimensional (1D) oxalate-bridged chains: cationic [Cu3(phen)3(H2O)Cr(C2O4)4]nn+ and anionic [Cu(phen)Cr(C2O4)3]nn− in 1 and ladder-like in 2. Both compounds contain two different bridging modes of the oxalate ligand between different metal centers − bis(bidentate) and mono-bidentate. Using chloranilate building block, black rod-like crystals of dinuclear chloranilate-bridged complex [(n-Bu)4N][Cu(H2O)2(phen)Cr(Cl2An)3]·7H2O·2CH3CN (3) are obtained. The characterization of the new complexes has been accomplished by means of the single crystal X-ray diffraction study, IR spectroscopy, thermal analysis (TG/DTA) and measurements on a SQUID magnetometer.

coordination and structural chemistry ; oxalate- and chloranilate building blocks

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