Síntese e caracterização de compostos mono e binucleares de rutênio e ferro com o LIGANTE 1,3-BIS(3-PIRIDILMETIL)2-TIOURÉIA (BPMT)

Abstract

Reactions of monocoordenative ions, such as [Ru(NH3)5(H2O)]2+ e [Fe(CN)5(NH3)]3-, with 1,3-bis(3-pyridylmethyl)-2-Thiourea (BPMT) lead to the formation of mononuclear complexes. Such complexes have been isolated and characterized by elemental analysis, electronic, vibrational in the infrared region, Mössbauer spectroscopy and electrochemical techniques (Cyclic voltammetry and differential pulse voltammetry). Backdonation interactions, dπ(M) → pπ*BPMT, of ruthenium pentaammines complexes are greater than pentacianoiron (II), which shows the π – acceptor action of cyanide ligands and the small energy of 3d orbital compared with 4d. Symmetric binuclear complexes, [(NH3)5Ru(μ–BPMT)Ru(NH3)5](PF6)4, Na6[(CN)5Fe(μ–BPMT)Fe(CN)5].4H2O, have been also isolated and characterized by electrochemical and spectroscopic techniques. Evaluation of the comproportionation constants indicated that such complexes present a considerable coupling between the metallic centers, following the behavior of binuclear complexes of class II. Unsymmetrical binuclear complex Na[(CN)5Fe(μ–BPMT)Ru(NH3)5] have been also synthesized and characterized. The values of the one – electron reduction potentials, the energies of the bands for metal – ligand charge transfer and the vibrational spectrum in the infrared region indicated a weak coupling between the metallic centers, which suggest that the cyanide ligands have a strong influence on the electronic density of the pentacyanoferrate complexes.