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Thermal and photochemical reactivity of ruthenium nitrosyl complexes: knowledge and control of the nitric oxide coordinated reactivity

Grant number: 99/07109-9
Support type:Research Projects - Thematic Grants
Duration: July 01, 2000 - June 30, 2005
Field of knowledge:Physical Sciences and Mathematics - Chemistry
Principal Investigator:Douglas Wagner Franco
Grantee:Douglas Wagner Franco
Home Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
Co-Principal Investigators:Alzir Azevedo Batista ; Elia Tfouni


The first research project was centered on the synthesis and characterization of ruthenium nitrosyl complexes. As a natural extension of this research proposal is dedicated to investigate the thermal and the photochemical reactivities of the previously isolated compounds, aiming to learn more about the N O ligand reactivity control.The thermal studies will deal primarily with the kinetic reactivity and thermodynamic stability of ruthenium nitrosyls on respect to nucleophilic reagents like OH-, RS- and N3 as indicated on the schemes below: [RuII - NO+]3+ + 2OH- [RuIINO2]+ + H2O (1) [RuII - NO+]3+ + RS- RSNO + [RuIIH2O]2+ (2) [RuII - NO+]3+ + N3- [RuII - H2O2+ + N2 + H2O (3) In the same item, special attention will be dedicated to investigate the reactions: [RuII - H2O]2+ + NO0 [RuII NO0]2+ (4) [RuIII - NO0]3+ [RuII - NO+]3+ (5) [RuIII - H2O]3+ + NO [RuII - NO+]3+ (6) [RuIII - NO0]3+ [RuII - NO+]3+ (7) The access to the kinetic and thermodynamic data for the above reactions would provide informations to better design model compounds which would work as NO scavengers and/or NO delivers. Still in the thermal reactivity subject, the electrochemical reduction of the NO+ ligand to other products than NO: NO-, N2H4 and NH3 will be investigated. Again the main goal is to understand and therefore gain some control over the coordinated NO ligand activation process.The preliminary results on the nitrosyl ruthenium tetraammines photochemical reactivity clearly indicate the existence of a photooxidation reaction (metal center oxidation and nitrosyl ligand reduction) followed by a NO0 thermal aquation: trans-[RuII(NH3)4L(NO+)]3+ h? trans-[RuIII(NH3)4L(NO0)]3+ (8) trans-[RuIII(NH3)4L(NO0)]3+ + H2O trans-[Ru(NH3)4L(H2O)]3+ + NO0 (9) This reaction is observed uppon irradition with light of energy corresponding to the bands located around 330 nm. Neither photooxidation, nor photoaquation reactions were observed when the irradiation was performed with light source of small energy (?irrad ? 380 nm). This behavior is on contrast with the exhibited photochemical reactivity of ruthenium(II) ammines which usually undergo ligand photosubstitution reactions: a) Ru(NH3)4LL']2+ h? [Ru(NH3)4(H2O)L']2+ + L (10) [Ru(NH3)4L(H2O)]2+ + L' [Ru(NH3)4(H2O)LL']2+ + NH3 Therefore, this nitrosyl photochemical reactivity study will be relevant in order to learn more how to control it. (AU)

Scientific publications (8)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
ZANICHELLI, PATRÍCIA GRAÇA; MIOTTO, ALEXANDRE M.; ESTRELA, HEDER F. G.; SOARES, FERNANDA ROCHA; GRASSI-KASSISSE, DORA M.; SPADARI-BRATFISCH, REGINA C.; CASTELLANO, EDUARDO E.; RONCAROLI, FEDERICO; PARISE, ALEJANDRO R.; OLABE, JOSÉ A.; ET AL. The [Ru(Hedta)NO](0,1-) system: structure, chemical reactivity and biological assays. Journal of Inorganic Biochemistry, v. 98, n. 11, p. 1921-1932, nov. 2004.
SCARPELLINI, MARCIELA; NEVES, ADEMIR; CASTELLANO, EDUARDO E.; FRANCO, DOUGLAS W. Structural, electrochemical and spectroscopic characterization of a new [Cu2L2([mu-Cl)(2)](2)[CuCl4](2) dimer complex. Journal of Molecular Structure, v. 694, n. 1-3, p. 193-198, Jun. 2004.
SILVA, WELTER C.; CASTELLANO, EDUARDO E.; FRANCO, DOUGLAS W. Structural and reactivity changes in ruthenium ammines induced by the NO ligand. Polyhedron, v. 23, n. 6, p. 1063-1067, mar. 2004.
CARLOS‚ R.M.; FERRO‚ A.A.; SILVA‚ H.A.S.; GOMES‚ M.G.; BORGES‚ S.S.S.; FORD‚ P.C.; TFOUNI‚ E.; FRANCO‚ D.W. Photochemical reactions of trans-[Ru (NH3)4 L (NO)]3+ complexes. Inorganica Chimica Acta, v. 357, n. 5, p. 1381-1388, 2004.
SCARPELLINI, MARCIELA; NEVES, ADEMIR; CASTELLANO, EDUARDO E.; NEVES, EDUARDO F. DE ALMEIDA; FRANCO, DOUGLAS W. A structural model for oxidized type II copper nitrite reductase with a polyimidazole tripodal ligand. Polyhedron, v. 23, n. 4, p. 511-518, fev. 2004.
SCARPELLINI, MARCIELA; TOLEDO JÚNIOR, JOSÉ CARLOS; NEVES, ADEMIR; ELLENA, JAVIER; CASTELLANO, EDUARDO E.; FRANCO, DOUGLAS W. Structural, spectroscopic and redox studies of a new ruthenium(III) complex with an imidazole-rich tripodal ligand. Inorganica Chimica Acta, v. 357, n. 3, p. 707-715, fev. 2004.
TFOUNI‚ E.; KRIEGER‚ M.; MCGARVEY‚ B.R.; FRANCO‚ D.W. Structure‚ chemical and photochemical reactivity and biological activity of some ruthenium amine nitrosyl complexes. Coordination Chemistry Reviews, v. 236, n. 1, p. 57-69, 2003.
BAGATIN‚ I.A.; DE ALMEIDA SANTOS‚ R.H.; FRANCO‚ D.W.; MAGALHAES‚ A.; FERREIRA‚ A.G. Spectroscopic and electrochemical properties of a new nitrosyl-complex of Ru (II): trans-(Ru (NO){(CH3CH2) 2PCH2CH2P (CH2CH3) 2} 2Cl)(PF6) 2. Inorganica Chimica Acta, v. 333, n. 1, p. 109-115, 2002.

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