Synthesis and Magnetism of μ‐Tetracarboxylato‐Bridged Dinuclear Oxovanadium(IV) Complexes

Three new dinuclear oxovanadium(IV) complexes bridged by a tetracarboxylato group (PMTA) and end‐capped with 5‐nitro‐1,10‐phenanthroline (NO₂phen), 2,9‐dimethyl‐1,10‐phenanthroline (Me₂phen) or 5‐methyl‐1,10‐phenanthroline (Mephen); namely [(VO)₂(μ‐PMTA)(NO₂phen)₂] (1), [(VO)₂(μ‐PMTA)(Me₂phen)₂] (2) and [(VO)₂(μ‐PMTA)(Mephen)₂] (3), have been synthesized and characterized by elemental analyses, molar conductivity, room‐temperature magnetic moment measurements, IR, ESR and electronic spectral studies. It is proposed that these complexes have PMTA‐bridged structures and consist of two oxovanadium(IV) ions, each in a square‐pyramidal environment. The complexes (1) and (2) were further characterized by variable temperature (4.2–300 K) magnetic susceptibility measurements, and the observed data were fitted to the modified Bleaney‐Bowers equation by the least‐squares method, giving the exchange integral J=− 3.69 cm⁻¹ for (1) and J=− 3.98 cm⁻¹ for (2). These results indicate that there is a weak antiferro‐magnetic spin‐exchange interaction between the two VO(IV) ions within each molecule.

This project was supported by the National Natural Science Foundation of China and the Natural Science Foundation of Shandong Province.

Keywords:

• dinuclear complexes
• magnetism
• tetracarboxylato‐bridge
• vanadium(IV) ion

Notes

This project was supported by the National Natural Science Foundation of China and the Natural Science Foundation of Shandong Province.