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Master's Dissertation
DOI
10.11606/D.75.2010.tde-27042010-082545
Document
Author
Full name
Daniela Ramos Truzzi
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2010
Supervisor
Committee
Franco, Douglas Wagner (President)
Giovani, Wagner Ferraresi de
Mauro, Antonio Eduardo
Title in Portuguese
Comportamento em solução de P(OH)(OEt)2 e P(OH)3 coordenados a tetraaminas de Ru(II)
Keywords in Portuguese
Ésteres de fósforo
Nitrosil
Tetraaminas de Ru(II)
Abstract in Portuguese
A estabilidade do ligante dietil fosfito foi analisada por 1H RMN em solução pH 1,0 e 3,0 a 25°C na presença e na ausência do íon [RuII(H2O)(NH3)5]2+. A hidrólise do dietil fosfito livre não foi observada em pH 3,0, enquanto na presença do íon [RuII(H2O)(NH3)5]2+, neste mesmo pH, esta reação foi observada (kobs=1,0.10-4 s-1). Em solução pH 1,0 a hidrólise ocorre tanto na presença do centro metálico (kobs=6,2.10-4 s-1) quanto na ausência (kobs=1,8.10-4 s-1). O complexo trans-[RuII(NO+)(NH3)4P(OH)3](Cl)3 foi sintetizado e caracterizado por técnicas espectroscópicas e espectrofotométricas. O espectro vibracional no estado sólido indicou que a νNO+ ocorre em duas frequências diferentes (1903 e 1867 cm-1) devido à presença do ligante P(OH)3 na forma protonada e desprotonada. O ENO+/NO0 foi determinado por Voltametria Cíclica em -0,52 V vs. ECS (0,5 mol L-1 CF3COOH, 25°C). O espectro eletrônico deste complexo apresentou três bandas nas regiões de 241nm (ε=1385 mol-1 L cm-1), 319 nm (ε=773 mol-1 L cm-1) e 500 nm (ε=20 mol-1 L cm-1). O valor de pKa para o ácido fosforoso no íon complexo trans-[RuII(NO+)(NH3)4P(OH)3]3+ foi determinado por meio de Espectroscopia Vibracional em solução (pKa=0,74 ±0,05). Como confirmado por Uv-vis, Voltametria Cíclica e Espectroscopia Vibracional, o íon trans-[RuII(NO+)(NH3)4P(OH)3]3+ sofre reação de aquação, dando origem ao ácido fosforoso livre e ao íon complexo trans-[RuII(NO+)(NH3)4(H2O)]3+ (λ=322 nm - ε=297 mol-1 L cm-1; ENO+/NO0=-0,40 vs. ESC; νNO+= 1849 cm-1). Dados de 31P 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.
Title in English
Behavior in solution of P(OH)(OEt)2 and P(OH)3 coordinated to ruthenium(II) tetraammines
Keywords in English
Nitrosyl
Phosphorus esters
Tetraammines of Ru(II)
Abstract in English
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.
 
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Publishing Date
2010-08-17
 
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