Synthesis and magnetism of μ-dioximato-bridged heterotrinuclear oxovanadium (IV)-palladium(II)-oxovanadium(IV) complexes

Four novel oxovanadium (IV)-palladium(II)-oxovanadium(IV) complexes heterotrinuclear complexes of the formula [(VO)2Pd(α-FD)2L2]SO4 where (α-FD)2- represents α-furildioximato and L denotes: 5-methyl-1,10-phenanthroline (Me-phen), 2,9-dimethyl-1,10-phenanthroline 5-chloro-1,10-phenanthroline (Cl-phen) and 5-bromo-1,10-phenanthroline (Br-phen), have been synthesized and characterized by elemental analyses, molar conductance and magnetic moments of room-temperature measurements, IR and electronic spectral studies. It is proposed that these complexes have extended dioximato-bridged structures and consists of two oxovanadium(IV) and the palladium(II) ions, In which the central palladium(II) ion has a square-planar environment end the end capped two oxovanadium(IV) ions have a square-pyramidal environment. The magnetic properties of complexes [(VO)2Pd(α-FD)2(Me-Phen)2]SO4 (1) and [(VO)2Pd(α-FD)2(Me2-Phen)2]SO4 (2)were investigated over the 4.2∼300 K range and correspond to what is expected for an antiferromagnetic VO(IV)-VO(IV) pair with SVO(IV) = 1/2 and SPd(II) = 0 (Pd2+ is a diamagnetic in a square-planar environment) local spins. The exchange integral (J) was evaluated as J = -7.28 cm-1 for (1) and J = -6.19 cm-1 for (2) based on Hamiltonian operator, H = -JS1S2. (author)