Contribuições conjuntas dos formadores de professores de Matemáticas e os professores indígenas de Terena para la revitalização da língua materna

This study may be understood as a set of ideas, experiences, and proposals about possible directions for indigenous teacher education when the purpose is revitalization of indigenous language in general and the use and valuation of indigenous language in mathematics education in particular. Taking as a point of departure the visions and needs of indigenous Terena teachers relative to native language fluency, we worked with them in one Terena village and produced effective materials for learning language and mathematics (mental calculation, measurements, spatial orientation). Our work focused on the involvement of native-language-speaking elders in early childhood education, especially indigenous language classes, bilingual schooling, and immersion in communal cultural practicesEste trabajo trae un conjunto de ideas, experiencias y propuestas sobre las posibles directivas a ser tomadas en la formación de maestros indígenas con el propósito de revitalizar las lenguas indígenas en general, y el uso de estas lenguas en la enseñanza de matemática en particular. El proyecto fue desarrollado en una comunidade Terena tomando como punto de partida la visión de los maestros Terena a respecto de sus necesidades, deseos y condiciones sobre el uso fluente de la lengua nativa. Junto a estos maestros fueron elaborados materiales para el aprendizaje de lengua y matemática (cálculos mentales, medidas, orientación espacial). El área de concentración fue la influencia del uso del lenguaje nativo por parte de los miembros mayores de la comunidad en la educación infantil, en especial, las clases de lengua nativa, la educación bilingüe, y actividades de imersión de los alumnos en prácticas culturales de la comunidadEste trabalho traz um conjunto de ideias, experiências e propostas sobre as possíveis diretivas a serem tomadas na formação de professores indígenas com o propósito de revitalizar as línguas indígenas em geral e o uso destas línguas no ensino de matemática em particular. O projeto foi desenvolvido em uma comunidade Terena tomando como ponto de partida a visão de professores Terena a respeito de suas necessidades, desejos e condições sobre o uso fonte da língua nativa. Junto a estes professores foram elaborados materiais para a aprendizagem de língua e matemática (cálculos mentais, medidas, orientação espacial). A área de concentração foi a influência do uso da linguagem nativa por parte dos idosos da comunidade na educação infantil, em especial, as classes de língua nativa, a educação bilíngue, e atividades de imersão dos alunos em práticas culturais da comunidad

Joint contributions of mathematics teacher educators and indigenous Terena teachers to revitalization of the native language Contribuciones conjuntas de los formadores de profesores de Matemáticas y los profesores indígenas de Terena para la revitalizació

This study may be understood as a set of ideas, experiences, and proposals about possible directions for indigenous teacher education when the purpose is revitalization of indigenous language in general and the use and valuation of indigenous language in mathematics education in particular. Taking as a point of departure the visions and needs of indigenous Terena teachers relative to native language fluency, we worked with them in one Terena village and produced effective materials for learning language and mathematics (mental calculation, measurements, spatial orientation). Our work focused on the involvement of native-language-speaking elders in early childhood education, especially indigenous language classes, bilingual schooling, and immersion in communal cultural practices. Keywords: Language revitalization, Terena people, Mathematics education. To understand the terms revitalization and revival as well as to be able to chose the appropriate set of instruments to implement such initiatives, one must carefully assess the current state of these languages. A language that has no native speakers is called dead or extinct. A language that has no native speakers in the youngest generation is called moribund. A language that has very few native speakers is called endangered or imperiled. T. Batista de Lima y A. Barbosa da Silva 122 Este trabajo trae un conjunto de ideas, experiencias y propuestas sobre las posibles directivas a ser tomadas en la formación de maestros indígenas con el propósito de revitalizar las lenguas indígenas en general, y el uso de estas lenguas en la enseñanza de matemática en particular. El proyecto fue desarrollado en una comunidade Terena tomando como punto de partida la visión de los maestros Terena a respecto de sus necesidades, deseos y condiciones sobre el uso fluente de la lengua nativa. Junto a estos maestros fueron elaborados materiales para el aprendizaje de lengua y matemática (cálculos mentales, medidas, orientación espacial). El área de concentración fue la influencia del uso del lenguaje nativo por parte de los miembros mayores de la comunidad en la educación infantil, en especial, las clases de lengua nativa, la educación bilingüe, y actividades de imersión de los alumnos en prácticas culturales de la comunidad. Descriptores: Revitalización de la lengua, Terena, Educación matemática. Este trabalho traz um conjunto de ideias, experiências e propostas sobre as possíveis diretivas a serem tomadas na formação de professores indígenas com o propósito de revitalizar as línguas indígenas em geral e o uso destas línguas no ensino de matemática em particular. O projeto foi desenvolvido em uma comunidade Terena tomando como ponto de partida a visão de professores Terena a respeito de suas necessidades, desejos e condições sobre o uso fonte da língua nativa. Junto a estes professores foram elaborados materiais para a aprendizagem de língua e matemática (cálculos mentais, medidas, orientação espacial). A área de concentração foi a influência do uso da linguagem nativa por parte dos idosos da comunidade na educação infantil, em especial, as classes de língua nativa, a educação bilíngue, e atividades de imersão dos alunos em práticas culturais da comunidade. Palavras-chave: Revitalização da língua, Terena, Educação matemática

Iridium-Catalyzed Hydrogenation of N-Heterocyclic Compounds under Mild Conditions by an Outer-Sphere Pathway

International audienceA new homogeneous iridium catalyst gives hydrogenation of quinolines under unprecedentedly mild conditions--as low as 1 atm of H2 and 25 °C. We report air- and moisture-stable iridium(I) NHC catalyst precursors that are active for reduction of a wide variety of quinolines having functionalities at the 2-, 6-, and 8- positions. A combined experimental and theoretical study has elucidated the mechanism of this reaction. DFT studies on a model Ir complex show that a conventional inner-sphere mechanism is disfavored relative to an unusual stepwise outer-sphere mechanism involving sequential proton and hydride transfer. All intermediates in this proposed mechanism have been isolated or spectroscopically characterized, including two new iridium(III) hydrides and a notable cationic iridium(III) dihydrogen dihydride complex. DFT calculations on full systems establish the coordination geometry of these iridium hydrides, while stoichiometric and catalytic experiments with the isolated complexes provide evidence for the mechanistic proposal. The proposed mechanism explains why the catalytic reaction is slower for unhindered substrates and why small changes in the ligand set drastically alter catalyst activity

Hydrogenation of Quinaldine and Benzylic Aldehydes both Separately and Combined in a Tandem Hydrogenation–Reductive Alkylation of Quinaldine by Aldehydes with Iridium Benzoquinoline Catalysts

A series of cyclometalated benzoquinoline complexes of Ir­(III) catalyze the hydrogenation of the heterocyclic ring of quinolines under mild conditions. Our best catalyst is active in a significantly wider range of solvents than our previous systems. In the presence of a suitable base, the Ir­(III) species is also able to hydrogenate the CO bonds of aldehydes. When quinolines and aldehydes are present together, the Ir­(III) complex catalyzes a tandem reaction in which the quinoline is first hydrogenated to a tetrahydroquinoline that is subsequently reductively alkylated by the aldehyde. The reductive alkylation competes with the hydrogenation of the aldehyde to the alcohol, and therefore good yields of the alkylated tetrahydroquinoline require the presence of excess aldehyde

Mild, Reversible Reaction of Iridium(III) Amido Complexes with Carbon Dioxide

Unlike some other Ir­(III) hydrides, the aminopyridine complex [(2-NH₂–C₅NH₄)­IrH₃(PPh₃)₂] (<b>1-PPh</b>_<b>3</b>) does not insert CO₂ into the Ir–H bond. Instead <b>1-PPh</b>_<b>3</b> loses H₂ to form the cyclometalated species [(κ²-<i>N</i>,<i>N</i>-2-NH-C₅NH₄)­IrH₂(PPh₃)₂] (<b>2-PPh</b>_<b>3</b>), which subsequently reacts with CO₂ to form the carbamato species [(κ²-<i>O</i>,<i>N</i>-2-OC­(O)­NH-C₅NH₄)­IrH₂(PPh₃)₂] (<b>10-PPh</b>_<b>3</b>). To study the insertion of CO₂ into the Ir–N bond of the cyclometalated species, a family of compounds of the type [(κ²-<i>N</i>,<i>N</i>-2-NR-C₅NH₄)­IrH₂(PR′₃)₂] (R = H, R′ = Ph (<b>2-PPh</b>_<b>3</b>); R = H, R′ = Cy (<b>2-PCy</b>_<b>3</b>); R = Me, R′ = Ph (<b>4-PPh</b>_<b>3</b>); R = Ph, R′ = Ph (<b>5-PPh</b>_<b>3</b>); R = Ph, R′ = Cy (<b>5-PCy</b>_<b>3</b>)) and the pyrimidine complex [(κ²-<i>N</i>,<i>N</i>-2-NH-C₄N₂H₃)­IrH₂(PPh₃)₂] (<b>6-PPh</b>_<b>3</b>) were prepared. The rate of CO₂ insertion is faster for the more nucleophilic amides. DFT studies suggest that the mechanism of insertion involves initial nucleophilic attack of the nitrogen lone pair of the amide on CO₂ to form an <i>N</i>-bound carbamato complex, followed by rearrangement to the <i>O</i>-bound species. CO₂ insertion into <b>1-PPh</b>_<b>3</b> is reversible in the presence of H₂ and treatment of <b>10-PPh</b>_<b>3</b> with H₂ regenerates <b>1-PPh</b>_<b>3</b>, along with Ir­(PPh₃)₂H₅

Mild, Reversible Reaction of Iridium(III) Amido Complexes with Carbon Dioxide

Unlike some other Ir­(III) hydrides, the aminopyridine complex [(2-NH₂–C₅NH₄)­IrH₃(PPh₃)₂] (<b>1-PPh</b>_<b>3</b>) does not insert CO₂ into the Ir–H bond. Instead <b>1-PPh</b>_<b>3</b> loses H₂ to form the cyclometalated species [(κ²-<i>N</i>,<i>N</i>-2-NH-C₅NH₄)­IrH₂(PPh₃)₂] (<b>2-PPh</b>_<b>3</b>), which subsequently reacts with CO₂ to form the carbamato species [(κ²-<i>O</i>,<i>N</i>-2-OC­(O)­NH-C₅NH₄)­IrH₂(PPh₃)₂] (<b>10-PPh</b>_<b>3</b>). To study the insertion of CO₂ into the Ir–N bond of the cyclometalated species, a family of compounds of the type [(κ²-<i>N</i>,<i>N</i>-2-NR-C₅NH₄)­IrH₂(PR′₃)₂] (R = H, R′ = Ph (<b>2-PPh</b>_<b>3</b>); R = H, R′ = Cy (<b>2-PCy</b>_<b>3</b>); R = Me, R′ = Ph (<b>4-PPh</b>_<b>3</b>); R = Ph, R′ = Ph (<b>5-PPh</b>_<b>3</b>); R = Ph, R′ = Cy (<b>5-PCy</b>_<b>3</b>)) and the pyrimidine complex [(κ²-<i>N</i>,<i>N</i>-2-NH-C₄N₂H₃)­IrH₂(PPh₃)₂] (<b>6-PPh</b>_<b>3</b>) were prepared. The rate of CO₂ insertion is faster for the more nucleophilic amides. DFT studies suggest that the mechanism of insertion involves initial nucleophilic attack of the nitrogen lone pair of the amide on CO₂ to form an <i>N</i>-bound carbamato complex, followed by rearrangement to the <i>O</i>-bound species. CO₂ insertion into <b>1-PPh</b>_<b>3</b> is reversible in the presence of H₂ and treatment of <b>10-PPh</b>_<b>3</b> with H₂ regenerates <b>1-PPh</b>_<b>3</b>, along with Ir­(PPh₃)₂H₅