Aos meus pais, Doralice e Marcos, pelo apoio, compreensão e, sobretudo, pelo amor. À minha irmã Renata pela sincera amizade. E ao Juliano pelas palavras de incentivo e confiança.
AgradecimentosAo Prof. Dr. Douglas Wagner Franco pela oportunidade de realizar este trabalho e, principalmente, pela atenção e ensinamentos a mim transmitidos. À FAPESP pelo auxílio financeiro. trans-[Ru II (NO + )(NH 3 ) 4 P(OH) 3 ] 3+ sofre reação de aquação, dando origem ao ácido fosforoso livre e ao íon complexo trans-[Ru II (NO + )(NH 3 ) 4 (H 2 O)] 3+ (λ=322 nm -ε=297 mol -1 L cm -1 ; E NO+/NO0 =-0,40 vs. ESC; ν NO+ = 1849 cm -1 ). Dados de 31 P RMN e Espectroscopia Vibracional sugerem que, anterior à dissociação do ligante P(OH) 3 , ocorre a formação de isômeros em que o ácido fosforoso pode estar coordenado ao centro metálico também pelo átomo de oxigênio. Os dados de experimentos cinéticos indicam que a dissociação do P(OH) 3 é dependente da concentração hidrogeniônica do meio.Abstract The stability of the ligand diethyl phosphite was analyzed by 1 H NMR in solution at pH 1.0 and 3.0 and 25 o C in the presence and in the absence of the ion [Ru II (H 2 O)(NH 3 ) 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 [Ru II (H 2 O)(NH 3 ) 5 ] 2+ , at this same pH, the reaction took place with k obs =1.0 10 -4 s -1 . In solution at pH 1.0 the hydrolysis reaction took place in the presence (k obs =6.2 10 -4 s -1 ) and in the absence (k obs =1.8 10 -4 s -1 ) of the metal center. The complex trans-[Ru II (NO + )(NH 3 ) 4 P(OH) 3 ](Cl) 3 was synthesized and characterized by spectroscopic and spectrophotometric techniques. Vibrational spectra showed a ν NO+ 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 E NO+/NO0 was determined by Cyclic Voltammetry at -0.52 V vs. SCE (0.5 mol L -1 CF 3 COOH, 25 o C). The electronic spectrum of this complexexhibited three bands at 241nm (ε=1385 L mol -1 cm -1 ), 319 nm (ε=773 L mol -1 cm -1 ) and 500 nm (ε=20 mol L -1 cm -1 ). The pK a value for the phosphorous acid in the complex íon trans-[Ru II (NO + )(NH 3 ) 4 P(OH) 3 ] 3+ was determined by Vibrational Spectroscopy in solution (pK a =0.74 ± 0.05). As judged from UV-vis, Cyclic Voltammetry and Vibrational Spectroscopy the ion trans-[Ru II (NO + )(NH 3 ) 4 P(OH) 3 ] 3+ suffer aquation reaction yelding free phosphorous acid and the ion complex trans-[Ru II (NO + )(NH 3 ) 4 (H 2 O)] 3+(λ = 322 nm -ε = 297 L mol -1 cm -1 ; E NO+/ NO0 =-0.40 vs. SCE; ν NO+ = 1893 cm -1 ). 31 P 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.