The studied heterometallic [CuFe] compounds, based on an [Fe(C2O4)3]3− building block and containing a 3D network or 1D ladder-like chains, were synthesized depending on whether the test tube with the same reaction layers was exposed to daylight or not.

A novel heterometallic oxalate-based compound of the formula {[Co(bpy)3][Mn2(C2O4)3]·H2O}n (1; bpy = 2,2'-bipyridine) was synthesized and characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction (XRD), and magnetization measurement. The molecular structure of 1 is made of a three-dimensional (3D) anionic network, [Mn2(C2O4)3]n(2n-), and tris-chelated cations [Co(bpy)3](2+) occupying the vacancies of the framework. Splitting between the zero-field-cooled (ZFC) and field-cooled (FC) branches of susceptibility below the small peak at 13 K indicates magnetic ordering. Compound 1 was used as a single-source precursor for the formation of the mixed-metal oxide CoMn2O4. This conversion via thermal decomposition was explored by thermal analysis (TGA and DTA), IR spectroscopy, powder XRD, and magnetic susceptibility measurement. From refined structural parameters, it could be seen that the spinel obtained by the thermal treatment of 1 at 800 °C is characterized by the inversion parameter δ = 21%, and therefore the structural formula at room temperature can be written as (tet)[Co(0.79)Mn(0.21)](oct)[Co(0.105)Mn(0.895)]2O4. The temperature dependence of magnetization for CoMn2O4 points to at least three magnetic phases: the ferrimagnetic state is observed below 83 K, and up to 180 K blocking of the magnetic moments of nanocrystallites of 31 nm appears, transforming to paramagnetic-like behavior above 180 K. Microstructural characterization of the CoMn2O4 sample was carried out by means of XRD line-broadening analysis.

A series of four novel mononuclear complexes of copper(II) with chloranilic acid and 2,2'-bipyridine were prepared and structurally characterised by X-ray structure analysis and IR spectroscopy. The complexes exhibit square-planar, square-pyramidal and octahedral coordination. The chloranilate dianion coordinates the Cu(II) atom in a terminal bidentate o-quinone-like mode forming a mononuclear complex species. The crystal packing of the aqua complex and the complexes with crystal water molecules are defined by hydrogen bonds. However, significant contributions are from interactions involving five-membered chelate rings with both types of ligands and intermolecular π-systems (bipyridine and chloranilate rings). The crystal packing of the complex with square planar Cu(II) coordination is dominated by interactions of the chelate rings with π-delocalised bonds and intermolecular π-systems. The occurrence of dimorphism could be related to the different types of these interactions in the stacks. The crystal packing of the octahedral complexes of the mono- and dihydrate solvates reveal 3D-networks with pores occupied by non-coordinated bipyridine molecules.

A series of six novel mononuclear, binuclear and linear one-dimensional (1D) compounds of copper(II) with chloranilic acid (3,6-dichloro-2,5-dihydroxybenzoquinone, H 2 CA) is prepared and a design strategy for the preparation of such complexes is discussed. Four described compounds are linear 1D coordination polymers [Cu(CA)] n , whereas another two involve a binuclear and a mononuclear, Cu 2 (CA) 3 and Cu(CA) 2 , core unit. A linear polymer incorporating bulky aromatic imidazole has been synthesized as a result of investigation of the influence of pH on the reaction mixture. Two coordination modes of the chloranilate dianion are observed. The bridging (bis)bidentate mode generates linear 1D polymeric species. Among these one reveals square-pyramidal coordination of Cu 2+ , whereas the three polymers contain Cu 2+ in an octahedral arrangement. However, the combination of both, terminal bidentate (ortho-quinone) and bridging (bis)bidentate modes of coordination produces a binuclear complex anion, which comprises a square-pyramidal coordination of Cu 2+ complex anions forming a supramolecular honeycomb-like network encapsulating 4,4 0 -bipyridine cations. When the chloranilate dianion coordinates the Cu 2+ atom only in a terminal bidentate mode, a mononuclear complex with an octahedral environment of the metal centre is formed. The presence of the bulky ancillary ligand imidazole produces an unprecedented packing involving chiral (racemic) and achiral (meso-compound) coordination polymers in the same crystal. Electron spin resonance spectroscopy of polycrystalline samples determined g-tensor parameters of copper(II) ions in different coordination geometries and revealed weak exchange interactions (|J| < 1 cm À1 ) in linear metal-complex polymers and dimeric species.