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| Author(s): |
Vagner Roberto de Souza
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2002-05-14 |
| Examining board members: |
Henrique Eisi Toma;
Ana Maria da Costa Ferreira;
Douglas Wagner Franco;
Marcelo Ganzarolli de Oliveira;
Denise de Oliveira Silva
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| Advisor: | Henrique Eisi Toma |
| Abstract | |
The chemistry of a series of ruthenium(II) and iron(II) complexes with N-heterocyclic Schiff bases was studied. The Schiff bases investigated here were derived from the condensation of 1,3-diaminopropane (or L-histidine) and 2-acetylpyridine (or acetylpyrazine). The reaction of the precursor RuCl3.3H2O with N,N\'-bis(7-methyl-2-pyridylmethylene)-1,3-diiminopropane (bapydip) and LiCl in ethanol led to the trans-[RuCl2(bapydip)] complex. Elemental analysis and 1H NMR data were consistent with the proposed formula. ln the presence of water, trans[RuCl2(bapydip )] spontaneously and quantitatively convert into trans[Ru(OH2)2(bapydip)]2+; the last one exhibiting efficient activity for the epoxidation of cyclohexene in the presence of iodosobenzene (PhlO). The new complex trans-[RuCl(NO)(bapydip)](PF6)2 was prepared by the addition of stoichiometric amounts of nitrite ion to acidic solution of the trans[RuCl2(bapydip )]. The results presented in this work demonstrate that the nitrosyl complex of ruthenium(II) is susceptible to addition reactions in the presence of a variety of nucleophiles and that the reduction potential of trans[RuCl(NO)(bapydip )](PF6)2 is biologically accessible. Preliminary photolysis experiments with trans-[RuCl(NO)(bapydip)](PF6)2 indicate the formation of NO and trans-[Ru(OH2)2(bapydip)]2+ species as products. The reaction of Fe(ClO4)2.6H2O with Schiff bases gave the complexes trans-[Fe(CH3CN)2(L)](ClO4)2 (L = bapydip, bapzdip) and [Fe(apyhist)2](ClO4)2. These compounds were characterized by elemental analysis, cyclic voltammetry, UV/Vis, Mõssbauer and 1H NMR spectroscopy. The electronic spectra of iron(II) complexes exhibited two strong bands around 520 and 620 nm, assigned to charge-transfer transitions (MLCT). The iron(II) compounds underwent substitution reactions in the presence of 2,2\'-bipyridine (bpy) leading to the [Fe(bpy)3]2+ complex, according to a pseudo first order behavior. The strong dependence of the rate constants with respect to the [bpy] indicated a dissociative character for the substitution reactions. In addition, the polyimine complex trans-[Fe(CH3CN)2(bapzdip)](ClO4)2 reacts with cis[Ru(bpy)2Cl2] leading to the trinuclear compound {(CH3CN)2Fe(bapzdip)[Ru(bpy)2Cl]2}(PF6)4, which was characterized on the basis of electronic, NMR spectroscopy and cyclic voltammetry. (AU) | |
| FAPESP's process: | 98/00399-9 - Spectroscopic investigation, thermal and electrochemical behaviors and reactivity of ruthenium (II) polyimine complexes |
| Grantee: | Vagner Roberto de Souza |
| Support Opportunities: | Scholarships in Brazil - Doctorate |