Synthesis, characterization and ferromagnetic spin-coupling between chromium(III) and copper(II) ions in oxamido bridged Cu(II)-Cr(III) dinuclear complexes

Four new heterodinuclear copper(II)-chromium(III) complexes bridged by dian ions of N,N'-oxamidobis(propionato)cuprate[Cu(obp)] and end-capped with 1,1 0-phenanthroline (phen), 5-nitro-1,10-phenanthrorine (NO2-phen), 5-chloro-1 ,10-phenanthroline (Cl-phen) or 5-bromo-1,10-phenanthroline (Br-phen); name ly [Cu(obp)Cr(L)(2)]NO3 (L = phen, NO2-phen, Cl-phen, Br-phen), have been s ynthesized and characterized by elemental analyses, IR and electronic spect ra studies, magnetic moments at room-temperature and molar conductivity mea surements. It is proposed that these complexes have extended oxamido-bridge d structures consisting of a copper(II) ion and a chromium(III) ion, which have a square-planar environment and an octahedral environment, respectivel y. The magnetic susceptibility of [Cu(obp)Cr(phen)(2)]NO3 complex was measu red between 4.2-300 K and the magnetic analysis was studied in detail, demo nstrating the operation of a ferromagnetic interaction between the adjacent chromium(III) and copper(II) ions through the oxamido-bridge within the co mplex. Based on spin Hamiltonian, (H ) over cap = -2J (S) over cap (1) . (S ) over cap (2), the exchange integral (J) was evaluated as +12.8 cm(-1).