Novel heteronuclear image-bridged trichloroacetates: synthesis and X-ray study of image and image

Three new heterotrinuclear trichloroacetates, View the MathML source[Fe2IIIMgIIO(CCl3COO)6(Py)3]·CH3C6H5(1), View the MathML source[Fe2IIIMgIIO(CCl3COO)6(THF)3](2) and View the MathML source[Fe2IIIZnIIO(CCl3COO)6(Py)3]·CH3C6H5(3), were synthesized and characterized by X-ray crystallography. For the first time, the structural data were obtained for μ3-oxotrinuclear complexes containing the transition and alkaline-earth metals in the cluster. Compounds 1–3 have a typical μ3-oxo trinuclear structure: (a) three metal atoms are situated in the apexes of the approximately equilateral (1, 3) or equilateral triangle (2); (b) μ3-oxygen atom and six trichloroacetic ligands fulfill the bridge functions; (c) the monodentate Py or THF ligands complete the octahedral geometry of the metal ions. It was found that the different distribution of Mg cations in the trimer that dictates by its own symmetry, Cs and C3. 1, has Cs symmetry with the mirror plane being perpendicular to the M3O fragment. One of the Fe atoms is situated in the special position, whereas the second one, residing in general position, is statistically disordered and alternates with the equal probability with Mg atom at the same site. This model was confirmed by the structure refinement and by the geometry of the cluster. In the crystal structure of 2, two crystallographically independent molecules have C3 symmetry and therefore in the crystal each metal site has to be occupied in 2/3 by Fe and in 1/3 by Mg ions. The packing of the molecules in the crystals and intermolecular interactions were analyzed.