Synthesis, characterization and ferromagnetic interaction in mu-oxamido Cu(II)-Cr(III) heterodinuclear complexes

Four new oxamido-bridged heterodinuclear copper(II)-chromium(III) complexes Cu(Me(2)oxpn)Cr(L)(2)](NO3)(3), where Me(2)oxpn denotes N,N'-bis(3-amino-2 ,2-dimethylpropyl)oxamido dianion and I, represents 1,10-phenanthroline (ph en), 5-nitro-1,10-phenanthroline (NO2-phen), 5-chloro-1,10-phenanthroline ( Cl-phen) and 5-bromo-1,10-phenanthroline (Br-phen), have been synthesized a nd characterized by elemental analyses, IR and electronic spectra, magnetic moments at room-temperature and molar conductivity measurements. It is pro posed that these complexes extend oxamido-bridged structures, consisting of planar copper(II) and octahedral chromium(III) ions. The variable temperat ure magnetic susceptibility (4.2-300 K) of complex [Cu(Me(2)oxpn)Cr(NO2-phe n)(2)](NO3)(3) was measured and the magnetic analysis was carried out by le ast square method to fit the data with equation derived from the spin Hamil tonian, (H) over cap= -2J (S) over cap(1) (S) over cap(2), giving the excha nge integrals J = +21.5 cm(-1), what indicates a ferromagnetic interaction between the adjacent chromium(III) and copper(II) ions through the oxamido- bridge within the complex.