Chemistry of water-soluble N-heterocyclic carbene platinum complexes

Water-soluble N-Heterocyclic Carbene (NHC) complexes of transition metal are currently captivated increasing attention because of a number of potential applications, such as biphasic catalysis. However, their chemical behavior in aqueous phase has been virtually unexplored so far. This PhD Dissertation concerns fundamental studies on the synthesis and reactivity of sulfonated NHC platinum complexes in water as a solvent, with special emphasis on the hydrolytic stability of Pt?C bonds. Several efficient protocols for their syntheses, and their limitations, have been uncover. The new complexes readily undergo a rich variety of different transformations (e.g., protonolysis, ligand substitution, oxidative addition/reductive elimination, controlled formation of water-soluble and stable nanoparticles, intramolecular C?H bond activations through a singular pathway, etc), and behave as convenient catalysts in the model processes tested here. The great majority of these reactions are quite straightforward and stereoselective, and in all of them ?and under a wide range of conditions (pH, temperature), the Pt?NHC bonds have been found to be fairly robust in aqueous medium. Thus, the presence of the sulfonated ligand, not only provides water-solubility, but also stability to the diversity of complexes studied in this solvent (halide, methyl, hydridealkynyl, ?-alkene, etc., derivatives), and to the new platinum nanoparticles presented here as well. It is remarkable that the persistent coordination of the ligand to the surface of the nanoparticles has been ambiguously demonstrated by determining the platinum?C(NHC) coupling constant for the first time for a nano-system. Finally, it is also worth to note that, according to DFT calculations, the remote sulfonate moiety assists intramolecular C?H bond cleavages, reducing considerably the Gibbs activation energy of the process (5?7 kcal/mol in the gas-phase) when compared to a conventional oxidative addition mechanism. The latter might open avenues to practical applications undergoing under friendly operational settings, far from the harsh reaction conditions often required for this kind of transformations

Chemistry of water-soluble N-heterocyclic carbene platinum complexes

Water-soluble N-Heterocyclic Carbene (NHC) complexes of transition metal are currently captivated increasing attention because of a number of potential applications, such as biphasic catalysis. However, their chemical behavior in aqueous phase has been virtually unexplored so far. This PhD Dissertation concerns fundamental studies on the synthesis and reactivity of sulfonated NHC platinum complexes in water as a solvent, with special emphasis on the hydrolytic stability of Pt?C bonds. Several efficient protocols for their syntheses, and their limitations, have been uncover. The new complexes readily undergo a rich variety of different transformations (e.g., protonolysis, ligand substitution, oxidative addition/reductive elimination, controlled formation of water-soluble and stable nanoparticles, intramolecular C?H bond activations through a singular pathway, etc), and behave as convenient catalysts in the model processes tested here. The great majority of these reactions are quite straightforward and stereoselective, and in all of them ?and under a wide range of conditions (pH, temperature), the Pt?NHC bonds have been found to be fairly robust in aqueous medium. Thus, the presence of the sulfonated ligand, not only provides water-solubility, but also stability to the diversity of complexes studied in this solvent (halide, methyl, hydridealkynyl, ?-alkene, etc., derivatives), and to the new platinum nanoparticles presented here as well. It is remarkable that the persistent coordination of the ligand to the surface of the nanoparticles has been ambiguously demonstrated by determining the platinum?C(NHC) coupling constant for the first time for a nano-system. Finally, it is also worth to note that, according to DFT calculations, the remote sulfonate moiety assists intramolecular C?H bond cleavages, reducing considerably the Gibbs activation energy of the process (5?7 kcal/mol in the gas-phase) when compared to a conventional oxidative addition mechanism. The latter might open avenues to practical applications undergoing under friendly operational settings, far from the harsh reaction conditions often required for this kind of transformations

Evaluación de la actividad puzolánica de un residuo de la industria del petróleo

En el presente artículo se presentan los resultados de la evaluación de la actividad puzolánica del catalizador gastado de craqueo catalítico (FCC), procedente de la industria del petróleo; con el fin de explorar la posibilidad de utilizar este desecho industrial como adición al cemento para la producción de concretos y morteros.La actividad puzolánica se determinó a partir de la resistencia a la compresión, según la norma ASTM C311 y C618.Igualmente se realizó el estudio aplicando las técnicas de Termogravimetría (TG) y Calorimetría Diferencial (DSC).Los resultados mostraron que este desecho puede ser utilizado como adición al cemento en morteros y concretos, sumándole la importancia de la utilización de un residuo industrial

Evaluación de la actividad puzolánica de un residuo de la industria del petróleo

En el presente artículo se presentan los resultados de la evaluación de la actividad puzolánica del catalizador gastado de craqueo catalítico (FCC), procedente de la industria del petróleo; con el fin de explorar la posibilidad de utilizar este desecho industrial como adición al cemento para la producción de concretos y morteros.La actividad puzolánica se determinó a partir de la resistencia a la compresión, según la norma ASTM C311 y C618.Igualmente se realizó el estudio aplicando las técnicas de Termogravimetría (TG) y Calorimetría Diferencial (DSC).Los resultados mostraron que este desecho puede ser utilizado como adición al cemento en morteros y concretos, sumándole la importancia de la utilización de un residuo industrial

Revisiting the synthesis of trans-[Pt(dmso)2ClMe] and cis-[Pt(dmso)2Me2]: Experimental and DFT studies

The preparation of trans-[Pt(dmso)2ClMe] (2) and cis-[Pt(dmso)2Me2] (3) from cis-[Pt(dmso)2Cl2] (1) and SnMe4has been reexamined (dmso = dimethyl sulfoxide). The information obtained from experimental and DFT studies has permitted the improvement of previously reported methods for the synthesis of both complexes in terms of reaction times, reaction yields, and atom economy. These studies show that complex 1reacts with a first equiv of SnMe4to form trans-[Pt(dmso)2ClMe] (2) as an intermediate that quickly reacts with a second equiv of SnMe4to yield cis-[Pt(dmso)2Me2] (3). When only 1 equiv of the organostannane reagent is added, the comproportionation of 3with the excess of unreacted 1leads the reaction back to the formation of trans-[Pt(dmso)2ClMe] (2). The mechanism of this comproportionation has been studied using DFT calculations