Synthesis, crystal structure and properties of a 4,4′-bipyridine bridged trigonal-bipyramidal copper homobinuclear complex with tris(2-aminoethyl)amine

The synthesis of the binuclear complex [(tren)Cu(4,4'-bipy)Cu(tren)] (ClO4)(4) where tren = tris(2-aminoethyl) amine and 4,4'-bipy=4,4'-bipyridine, is described. Single-crystal X-ray diffraction study of the homo-binuclear complex shows that two copper(II) ions are bridged by 4,4'-bipyridine and each copper(II) ion is tr-igonal-bipyramidally coordinated, with tren occupying four sites [Cu-N=2.030(2), 2.047(2), 2.078(2), and 2.119(2) Angstrom respectively] and a bridging 4,4'-bipyridine in the apical position. The Cu-Cu distance is 11.11 Angstrom. In variable-temperature ESR spectra, the presence of hyperfine structure suggest that some interaction exists between the two copper(II) ions. Temperature-dependent susceptibility studies indicate that it is a weak ferromagnetic interaction with 2J = 1.23 cm(-1).