Obtenção de nanossistemas magnéticos através de blocos construtores com o ligante bis(2-piridilcarbonil)-amideto (bpca)

Abstract

In this work was carried out the synthesis of trinuclear compounds and bimetallic systems, being their magnetic properties studied. In addition, new inorganic complexes were prepared in an attempt to use them as a bridge ligand. Initially, for the synthesis of the trinuclear compounds, the precursors of the type [Cu(opba)]2-, [Mn(opba)]1- and the building blocks [Cu(bpca)]+1 and [Fe(bpca)]+2 were prepared; being opba= ortho-phenylenebis(oxamate) and bpca= anion bis (2-piridilcarbonil)-amide. It was possible to obtain four novel trinuclear compounds from the reactions using the precursors, as follows: [Cu(bpca)]2[Cu(opba)]DMSO3H2O, [Cu(bpca)]2[Cu(opba)(H2O]DMSO3H20, [Cu(bpca)]2[Mn(opba)]NO37H2O and [Fe(bpca)]2[Mn(opba)]Cl3. The compounds [Cu(bpca)]2[Cu(opba)]DMSO3H2O and [Cu(bpca)]2[Mn(opba)]NO37H2O exhibit antiferromagnetic interaction between their metallic ions, and at 300 K their MT values are equal to 1.129 and 2.17 emu mol-1 K, respectively. The MS values, obtained from measurements of the magnetization as a function of the applied field, were compared with calculated values. Two new compounds containing [Cu(bpca)]+1 and the opba as ligand, [Cu2(bpca)2(opba)]23H2O and [Cu(bpca)(opba)], were synthesized and also their structures were determined by single crystal X-ray crystallography. Afterwards, the precursors: [Ni(dmit)]-2, [Ni(dmit)]-1, [Fe(bpca)2]+1, [Cu(bpca)2] e [Cu(pia)(H2O)](NO3)2 were synthesized, where dmit is 1,3-dithiol-2-thione-4,5-dithiolate and pia is 2-pyridine carboxyamide. From them, it was possible to acquire four novel bimetallic systems: (Bu4N)[Fe(bpca)2][Ni(dmit)2]2H2O, [Fe(bpca)2][Ni(dmit)2], [Fe(bpca)][Ni(dmit)2]H2O and [Cu(pia)][Cu(bpca)2][Ni(dmit)2]NO32CH3OH. The Compounds (Bu4N)[Fe(bpca)2][Ni(dmit)2]2H2O and [Cu(pia)][Cu(bpca)2][Ni(dmit)2]NO32CH3OH present ferromagnetic and antiferromagnetic interaction, respectively, between their metallic ions and at 300 K, their values of MT are equal to 1.129 and 2.17 emu mol-1 K, respectively. The values of MS obtained experimentally from measurements of magnetization as a function the applied field were compared with calculated values.