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Synthesis and Ferromagnetic Interaction in Oxamido-Bridged Copper(II)-Chromium(III) Heterotetranuclear Complexes

Wang S., Li Y., Yan C.

Polish Journal of Chemistry

2006

Vol. 80, nr 8

1327-1336

Two new mi-oxamido-bridged copper(II)-chromium(III) heterotetranuclear complexes formulated as [Cu3 (dmoxae)3Cr](ClO4 )3 (1) and [Cu3(dmoxpn)3Cr](ClO4)3 (2), where dmoxae and dmoxpn represent N,N'-bis[2-(dimethylamino)ethyl]oxamido and N,N'-bis[3-(dimethylamino)propyl]oxamido dianions, respectively, have been synthesized and characterized by the elemental analyses, spectroscopic (IR, UV, ESR) studies, magnetic moments (at room-temperature) and by molar conductivity measurements. It is proposed that these complexes have oxamido-bridged structures consisting of three copper( II) ions and a chromium(III) ion, in which the chromium(III) ion has an octahedral environment and the three copper(II) ions have a square-planar environment. The two heterotetranuclear complexes were further characterized by variable-temperature magnetization (3~300 K) measurements and the magnetic data have been used to deduce the indicated heterotetranuclear structure. The results derived from least-squares fit of the experimental data have confirmed that the operation of a ferromagnetic interaction between the adjacent copper(II) and chromium(III) ions occurs through the oxamidobridge within each molecule. On the basis of the spin Hamiltonian operator, H= - 2J(S cu . S cr + S cu2 . S cr + S cu2 . S cr ), the magnetic analyses were carried out for the two copper(II)-chromium(III) heterotetranuclear complexes and the spin-coupling constants (J)were evaluated as +9.28 cm-1 for (1) and+9.63 cm-1 for (2). The influence of the symmetry of the magnetic orbitals on the nature of the magnetic interaction between the paramagnetic centers is preliminary discussed.

Synthesis and Characterization of Three Novel Ferromagnetic Copper(II) Binuclear Complexes Bridged by Phthalato

Ma S., Zhang L. Z.

Polish Journal of Chemistry

2002

Vol. 76 / nr 11

1537-1543

Three novel copper(II) binuclear complexes with phthalate dianion as bridging ligand have been obtained, namely [Cu2(phth)(L)4](ClO4)2, where phth denotes the phthalate dianion and L represents 1,10-phenanthroline (abbreviated as phen), 2,2_-bipyridine (bpy) or 4,4_-dimethyl-2,2_-bipyridine (Me2bpy). Meanwhile, the IR, electronic spectra, ESR spectra and the temperature-dependent magnetic susceptibility of the three complexes were analyzed. The results of the magnetic analyses show a weak ferromagnetic coupling between the paramagnetic ions in all complexes studied.

Syntesis and Ferromagnetic Interaction in Oxalato-Bridged Copper(II)-Chromium(III)-Copper(II) Heterotrinuclear Complexes

Li Y., Yan C. -W., Guan S. -H.

Polish Journal of Chemistry

2002

Vol. 76 / nr 12

1655-1663

Synthesis, Characterization and ferromagnetic Interaction in M-Oxamino Cu(II)-Cr(III) Heterodinuclear Complexes

Li Y., Yan C., Zeng X.

Polish Journal of Chemistry

2000

Vol. 74, nr 8

1055-1062

Synthesis and ferromagnetic oxamido-bridged heterodinuclear copper(II)-chromium(III) complexes

Yan C.-W., Li Y.-T.

Polish Journal of Chemistry

1998

Vol. 72, nr 5

844-851

Four new my-oxamido heterodinuclear complexes [Cu(oxap)Cr(L)2](NO3)3, where oxap denotes the N