Full text
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| Author(s): |
Daniela Ramos Truzzi
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT) |
| Defense date: | 2010-02-19 |
| Examining board members: |
Douglas Wagner Franco;
Wagner Ferraresi de Giovani;
Antonio Eduardo Mauro
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| Advisor: | Douglas Wagner Franco |
| Abstract | |
The stability of the ligand diethyl phosphite was analyzed by 1H NMR in solution at pH 1.0 and 3.0 and 25°C in the presence and in the absence of the ion [RuII(H2O)(NH3)5]2+. The hydrolysis of the free diethyl phosphite in solution at pH 3.0 was not observed, while in the presence of the ion [RuII(H2O)(NH3)5]2+, at this same pH, the reaction took place with kobs=1.0 10-4 s-1. In solution at pH 1.0 the hydrolysis reaction took place in the presence (kobs=6.2 10-4 s-1) and in the absence (kobs=1.8 10-4 s-1) of the metal center. The complex trans-[RuII(NO+)(NH3)4P(OH)3](Cl)3 was synthesized and characterized by spectroscopic and spectrophotometric techniques. Vibrational spectra showed a νNO+ in the solid state at two differents frequencies (1903 and 1867 cm-1) due to the presence of the ligand P(OH)3 in the protonated and deprotonated forms. The ENO+/NO0 was determined by Cyclic Voltammetry at -0.52 V vs. SCE (0.5 mol L-1 CF3COOH, 25°C). The electronic spectrum of this complex exhibited three bands at 241nm (ε=1385 L mol-1 cm-1), 319 nm (ε=773 L mol-1 cm-1) and 500nm (ε=20 mol L-1 cm-1). The pKa value for the phosphorous acid in the complex íon trans-[RuII(NO+)(NH3)4P(OH)3]3+ was determined by Vibrational Spectroscopy in solution (pKa=0.74 ± 0.05). As judged from UV-vis, Cyclic Voltammetry and Vibrational Spectroscopy the ion trans-[RuII(NO+)(NH3)4P(OH)3]3+ suffer aquation reaction yelding free phosphorous acid and the ion complex trans-[RuII(NO+)(NH3)4(H20)]3+ (λ=322 nm - ε=297 L mol-1 cm-1; ENO+/NO0=-0.40 vs. SCE; νNO+= 1893 cm-1). 31P NMR and Vibrational Spectroscopy data suggest that, before the dissociation of the P(OH)3 ligand, occurs the formation of linkage isomers in which the phosphorous acid can be coordinated to the metal center also by the oxygen atom. The data obtained by kinetics experiments suggest that the P(OH)3 dissociation is dependent of the hydrogen ionic concentration of the medium. (AU) | |
| FAPESP's process: | 08/02014-0 - Nucleophilic attack of the OH- ions to the complex trans-[Ru(NO)(NH3)4P(III)]X3, P(III)=P(O)(H)(OEt)2 and P(OtBut)3 |
| Grantee: | Daniela Ramos Truzzi |
| Support Opportunities: | Scholarships in Brazil - Master |