Bielefeld, Universiẗat, Diss., 2001.

Köln, University, Diss., 2002.

Th. 3e cycle--Génie chim.--Nancy--I.N.P.L., 1982.

with Professor John O'Malley, Weston Jesuit School of Theology, moderated by Dr. Patricia Deleeuw, Associate Academic Vice President / Gasson Hall 100

Thèses (Ph.D.)--Université de Sherbrooke (Canada), 1999. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

A autoxidação dos complexos de Ni(II) e Co(II) com tetra, penta e hexaglicina, em meio de tampão borato, é acelerada por espécies de enxofre (IV) (H2S0<SUB3, HS03-e SO32-). A formação dos complexos de Ni(III) e Co(III) foi acompanhada espectrofotometricamente em 325 e 265 nm, respectivamente. A velocidade da reação de autoxidação do complexo de Ni(II)/Gn aumenta com a concentração de S(IV) e é máxima em pH &#926;8,5. O processo é autocatalítico com Ni(III)ou Co(III)atuando como iniciadores, forma~os pela oxidação espontânea de Ni(II) ou Co(II) pelo oxigênio molecular. A dependência da constante de velocidade observada com a oncentração de S(IV) evidenciou possíveis reações paralelas com formação de um complexo com ligantes mistos antes da etapa da oxidação. A autoxidação dos complexos de Cu(II)com penta e hexaglicina em pH =9 é muito lenta, na presença e na ausência de S(IV).A presença de S(IV) e de traços de Ni(II)ou Co(II) aumenta significativamente a velocidade e a eficiência da reação (período de indução de 0,5 s). O mecanismo envolve uma cadeia de reações e um ciclo redox dos complexos. Acetaldeído e formaldeído inibem parcialmente a reação de autoxidação de Ni(II)/G4 na presença de S(IV) e luminol.O método quimiluminescente desenvolvido pode ser empregado para determinação de formaldeído [(5,0.10-5 - 1,0.10-2) mol L-1] e acetaldeído [(1,0.10-4 - 0,10) mol L-1], não sendo possível detectar separadamente cada um desses aldeídos. Na autoxidação de Ni(OH)2 induzida por S(IV) na presença de luminol ocorre emissão de radiação, possibilitando a detecção de S(IV) na faixa de 5,0.10-8 a 1,0.10-5 mol L-1, com limite de detecção estimado de 1,3.10-8 mol L-1. / The autoxidation of Ni(lI) and Co(lI) complexes with tetra, penta and hexaglycine, in borate medium, is accelerated by sulfur (IV) species (H2S03, HS03- and SO32-). The formation of Ni(llI) and Co(lIl) complexes was followed spectrophotometrically at 325 and 265 nm, respectively. The autoxidation rate of Ni(II)/Gn complex increases with S(IV) concentration and is maximum at pH ~ 8.5. The process is autocatalytic with Ni(lIl) or Co(llI) acting as initiators, formed by spontaneous oxidation by oxygen. The dependence of the observed rate constant with S(IV) concentration showed evidences of back or parallel reactions with formation of mixed ligand complex prior to the oxidation step. The autoxidation of Cu(II)/penta and hexaglycine complexes at pH = 9, in the presence and absence of S(IV), is very slow. The presence of S(IV) and of small amounts of Ni(lI) or Co(lI) increases significantly the effectiveness and reaction rate (induction period = 0.5 s). The mechanism involves a radical chain and redox cycling of the metal íon complexes. Acetaldehyde and formaldehyde partially inhibit the autoxidation reaction of Ni(II)/G4 in the presence of S(IV) and luminol. The developed chemiluminescent method can be used for determination of formaldehyde [(5.0.10-5 - 1.0.10-2) mol L-1] and acetaldehyde [(1.0.10-4 - 0.10) mol L-1), being not possible their isolated detection. The S(IV) induced autoxidation of Ni(OH)2 in the presence of luminol, occurs with radiation emission, allowing S(IV) detection in the range 5.0.10-8 to 1.0.10,-5 mol L-1, with detection limit of 1.3.10-8 mol L-1.

A autoxidação dos complexos de Ni(II) e Co(II) com tetra, penta e hexaglicina, em meio de tampão borato, é acelerada por espécies de enxofre (IV) (H2S0<SUB3, HS03-e SO32-). A formação dos complexos de Ni(III) e Co(III) foi acompanhada espectrofotometricamente em 325 e 265 nm, respectivamente. A velocidade da reação de autoxidação do complexo de Ni(II)/Gn aumenta com a concentração de S(IV) e é máxima em pH &#926;8,5. O processo é autocatalítico com Ni(III)ou Co(III)atuando como iniciadores, forma~os pela oxidação espontânea de Ni(II) ou Co(II) pelo oxigênio molecular. A dependência da constante de velocidade observada com a oncentração de S(IV) evidenciou possíveis reações paralelas com formação de um complexo com ligantes mistos antes da etapa da oxidação. A autoxidação dos complexos de Cu(II)com penta e hexaglicina em pH =9 é muito lenta, na presença e na ausência de S(IV).A presença de S(IV) e de traços de Ni(II)ou Co(II) aumenta significativamente a velocidade e a eficiência da reação (período de indução de 0,5 s). O mecanismo envolve uma cadeia de reações e um ciclo redox dos complexos. Acetaldeído e formaldeído inibem parcialmente a reação de autoxidação de Ni(II)/G4 na presença de S(IV) e luminol.O método quimiluminescente desenvolvido pode ser empregado para determinação de formaldeído [(5,0.10-5 - 1,0.10-2) mol L-1] e acetaldeído [(1,0.10-4 - 0,10) mol L-1], não sendo possível detectar separadamente cada um desses aldeídos. Na autoxidação de Ni(OH)2 induzida por S(IV) na presença de luminol ocorre emissão de radiação, possibilitando a detecção de S(IV) na faixa de 5,0.10-8 a 1,0.10-5 mol L-1, com limite de detecção estimado de 1,3.10-8 mol L-1. / The autoxidation of Ni(lI) and Co(lI) complexes with tetra, penta and hexaglycine, in borate medium, is accelerated by sulfur (IV) species (H2S03, HS03- and SO32-). The formation of Ni(llI) and Co(lIl) complexes was followed spectrophotometrically at 325 and 265 nm, respectively. The autoxidation rate of Ni(II)/Gn complex increases with S(IV) concentration and is maximum at pH ~ 8.5. The process is autocatalytic with Ni(lIl) or Co(llI) acting as initiators, formed by spontaneous oxidation by oxygen. The dependence of the observed rate constant with S(IV) concentration showed evidences of back or parallel reactions with formation of mixed ligand complex prior to the oxidation step. The autoxidation of Cu(II)/penta and hexaglycine complexes at pH = 9, in the presence and absence of S(IV), is very slow. The presence of S(IV) and of small amounts of Ni(lI) or Co(lI) increases significantly the effectiveness and reaction rate (induction period = 0.5 s). The mechanism involves a radical chain and redox cycling of the metal íon complexes. Acetaldehyde and formaldehyde partially inhibit the autoxidation reaction of Ni(II)/G4 in the presence of S(IV) and luminol. The developed chemiluminescent method can be used for determination of formaldehyde [(5.0.10-5 - 1.0.10-2) mol L-1] and acetaldehyde [(1.0.10-4 - 0.10) mol L-1), being not possible their isolated detection. The S(IV) induced autoxidation of Ni(OH)2 in the presence of luminol, occurs with radiation emission, allowing S(IV) detection in the range 5.0.10-8 to 1.0.10,-5 mol L-1, with detection limit of 1.3.10-8 mol L-1.

This theses presents the synthesis and characterization of Cd(II)-, Pb(II)- and Hg(II)-aminoethanethiolates in aqueous media. 2-Aminoethanethiolate, a versatile sulfur andnitrogen (S/N) based ligand was used due to its resemblance to the naturally occurringamino acid, cysteine. The work is presented in four major parts: first, backgroundinformation on the versatile structural chemistry of Cd, Pb and Hg-thiolates with S/Ncontaining ligands; second, synthesis and characterization of Cd(II) with 2-aminoethanethiolates; third, synthesis and characterization and structural chemistry ofPb(II) with 2-aminoethanethiolates; and fourth, synthesis and characterization of Hg(II)-2-aminoethanethiolates in solution- and solid-state with emphasis on the mechanisticpathways for the formation of clusters.The compounds reported here are synthesized by direct addition of the metal saltsand the ligand in deionized water. For Cd(II)-thiolates, insoluble products (77 - 80 and 82- 84) due to the formation of oligomers and polymers were obtained. In Pb(II)-thiolates(85 - 89), the structural chemistry is variable due to the extensive array of coordinationenvironments Pb can acquire. This can be related to the stoichiometry of the reaction aswell as the reaction conditions. The structural trends in Cd(II)- and Pb(II)-thiolates arenot observed in the Hg(II)-thiolates. Rather the halide influences the formation ofmolecular as well as non-molecular structures. Systematic pathways for the formation ofthe compounds based on a variety of commonly observed structural 'building blocks' arepresented. For Cl, Br derivatives, a four-coordinate intermediate, [Hg(SR)2X2] (88 - 96)and for I derivatives three-coordinate intermediates, [HgI(SR)2] and [HgI2(SR)] (97 -100) can be considered as building units. The compounds were characterized withIR/Raman, NMR, MS, Uv-Vis and X-ray crystallography.

No description available.

La thèse se concentre sur la synthèse et la caractérisation de nouveaux complexes de manganèse comme alternative possible aux complexes de gadolinium, actuellement les agents de contraste de choix pour l’Imagerie par Résonance Magnétique (IRM). Dans cette perspective, nous nous sommes intéressés à trois groupes de ligands pentadentés pour la complexation de Mn2+. Des nombres de coordination de 6 ou 7 ont été déterminés par cristallographie pour ces complexes, permettant la coordination d’une ou deux molécules d’eau en première sphère de coordination de Mn2+. La stabilité thermodynamique de ces complexes est plus faible que celle de complexes polyaminocarboxylates et leur dissociation est très rapide comparée à [Mn(nota)] et [Mn(dota)]2-. Seuls les complexes de Mn2+ avec des ligands macrocycliques à 12 atomes sont oxydés en Mn3+ à l’air. Les relaxivités des complexes bishydratés sont deux fois plus élevées que celles des complexes monohydratés et elles sont comparables à celles des agents de contraste commerciaux. Les données de RMN d’17O mesurées à différentes températures ont montré que l’échange d’eau peut être lent, intermédiaire, ou rapide selon le ligand. Les mesures à hautes pressions ont confirmé que le mécanisme d’échange est de type dissociatif pour les complexes avec un nombre de coordination de 7 et de type associatif pour les complexes avec un nombre de coordination de 6. Les petits anions bidentés endogènes peuvent remplacer une molécule d’eau dans les complexes bishydratés de macrocycles pentaazotés à 15 atomes, alors que pour les autres soit le complexe se décompose, soit il n’y a pas d’influence. / The thesis is focused on the synthesis and characterization of novel manganese complexes as alternative to Gd3+ chelates which are wide-spread contrast agents in Magnetic Resonance Imaging (MRI). In this perspective, three structurally different groups of pentadentate ligands for Mn2+ complexation have been investigated. Coordination numbers of 6 or 7 were determined in the crystal structure of the Mn2+ complexes enabling one or two water molecules in the first sphere. The thermodynamic stability of the chelates is lower than that of polyaminocarboxylate complexes and their dissociation is very fast in comparison to [Mn(nota)] and [Mn(dota)]2–. Only Mn2+ complexes with 12- membered ligands undergo oxidation in air to Mn3+ species. The proton relaxivities of the bishydrated complexes are two times higher than those for monohydrated complexes and are comparable to those of commercial contrast agents. Variable-temperature 17O NMR data revealed that the water exchange varies from slow to intermediate or to extremely fast, depending on the ligand. High-pressure 17O NMR measurements confirmed dissociative water exchange mechanism on complexes with CN = 7 and associative mechanism on complexes with CN = 6. Small endogenous bidentate anions are capable of replacing only one water molecule in the bishydrated complex with the 15-membered pentaaza ligand (L2), while in other cases the complex is decomposed or no influence is observed.