Synthesis, crystal structures and physical properties of two terephthalate-bridged copper(II) and nickel(II) complexes

Two mu (2)-terephthalate (tp) bridged complexes, [Cu-2(tp)(pren)(4)](ClO4)( 2) (pren = 1,3-diaminopropane) (1) and [Ni-2(tp)(pren)(4)(Him)(2)](ClO4)(2) (Him = imidazole) (2), have been synthesized and characterized by X-ray si ngle-crystal structural analysis. In the discrete dinuclear [Cu-2(tp)(pren) (4)](2+) cation of complex (1), each Cu-II atom has a square-pyramidal geom etry, being coordinated by four nitrogen atoms (avg. 2.031 Angstrom) from t wo pren ligands at the basal plane and one oxygen atom [2.259(3) Angstrom] from a bis-monodentate tp group at the axial position. In the discrete dinu clear [Ni-2(tp)(pren)(4)(Him)(2)](2+) cation of complex (2), each Ni-II cen ter is coordinated by five nitrogen atoms [Ni-N 2.069(3)-2.109(2) Angstrom] from one Him group and two pren groups, and completed by one oxygen atom [ Ni-O 2.138(3) Angstrom] from a bis-monodentate tp group to furnish a distor ted octahedron. Magnetic susceptibility studies show that the pair of metal atoms, although being separated by > 11.5 Angstrom, exhibit weak intramole cular antiferromagnetic interactions in complexes (1) (g = 2.07 and J = -3. 4 cm(-1)) and (2) (g = 2.10 and J = -0.7 cm(-1)). The electrochemical behav iors of the complexes have also been studied by cyclic voltammogram process es.