engleski

Heterometallic compounds containing tris(phenantroline)nickel(II) cations and (oxalato)tantalum(V) complex anions

Synthesis of new complex compounds with desired and predictable physical properties (mechanical, optical, electrical, magnetic, catalytic...) is usually based on controlled supramolecular linking of molecular entities. Systems with supramolecular arrangement involve ligands that are simultaneously coordinated to the metal ion and contain potential sites for intermolecular interaction (hydrogen bonding, π-π-interaction, van der Waals forces). A frequently used approach for the synthesis of this kind of species consists in using mononuclear anionic oxalate complexes as ligands toward other transition-metal complex cations. This approach is known as building-blocks chemistry. Our transition-metal complex systems were obtained by merging [Ni(phen)3]2+ (phen = 1, 10-phenanthroline) cations, and oxalate complex anions of tantalum(V). It was found that the coordination sphere around the tantalum ion is subject to change due to the solvent change. Thus, by conducting crystallisation from a water/ethanol (ratio 1 : 2) solution we have isolated a very stable compound of the composition [Ni(phen)3][Ta(OC2H5)(C2O4)3]•H2O ; however when methanol was used instead of ethanol, the compound [Ni(phen)3][Ta(OCH3)(C2O4)3]•H2O formed. The new compounds were characterized by the following methods: IR and UV/Vis spectroscopy, TG/DTA analysis, single-crystal X–ray diffraction and magnetic susceptibility measurements (using the Gouy balance).

Heterometallic compounds; phenantroline; nickel; tantalum; oxalate

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