Reacciones de formación de enlaces C-C y C-N catalizadas por complejos de cobre y oro

Los trabajos que se presentan en esta Memoria describen la síntesis y caracterización asi como actividad catalítica de complejos de cobre(I) y oro(I) con ligandos del tipo tris(pirazolilmetil)amina, tris(pirazolil)metano benos N-heterocíclicos en reacciones de formación de enlaces C-C y C-N. Esta Tesis Doctoral se divide en cuatro Capítulos. El primero describe la preparación y caracterización estructural de nuevos complejos de cobre (I) con ligandos del tipo tris(pirazolilmetil) amina (Tpax). Asimismo, se estudian las capacidades catalíticas de estos complejos en reacciones de inserción de carbenos y nitrenos a sustratos saturados e insaturados comparando de este modo la actividad catalítica que presentan estos complejos con la observada con otros complejos de cobre(I) con ligandos tridentados ya conocidos, como son s(pirazolil) borato (Tpx) y el tris(pirazolil) metano (Tpmx). En el segundo Capítulo de esta Tesis Doctoral se describe el uso de complejos de cobre(I) con ligandos tris (pirazolil)borato (Tpx) en reacciones de funcionalización de enlaces C-H de derivados del indol utilizando compuestos como fuente carbénica. Dado que la reacción transcurre a través de un intermedio propano, se ha podido llevar a cabo, de manera consecutiva, la funcionalización de las posiciones C2 y C3 indol. Asimismo, se han realizado estudios mecanísticos para elucidar el mecanismo de reacción de ionalización índoles mediante transferencia de carbenos. n el tercer Capítulo de esta Tesis Doctoral se presenta la síntesis y caracterización de nuevas sales de azolio fluoradas precursoras de ligandos NHC y se han preparado los correspondientes complejos de Cu(I) i(I). Por otro lado, estos nuevos complejos de oro se han empleado como catalizadores en la reacción de ionalización de metano con el diazoacetato de etilo utilizando C02 supercrítico como disolvente de la reacción. El último capítulo de esta Tesis Doctoral está dedicado al estudio de la capacidad catalítica de los complejos NHC-Au(I) en la reacción de Mannich entre iminas y compuestos 1,3-dicarbonílicos. Este Capítulo está escrito en inglés, para cumplir con la normativa vigente de la Universidad de Huelva para poder optar al título de Doctorado Internacional.This PhD Thesis describes the synthesis and characterization as well as the catalytic activity of copper(I) and gold(I) complexes with tris(pyrazolylmethyl)amine, tris(pyrazolyl)borate and N-heterocyclic carbenes ligands in C-C and C-N bonds forming reactions. This Thesis is divided in four Chapters. The first one describes the preparation and structural characterization of new copper(l) complexes with tris(pyrazolylmethyl)amine (Tpax) ligands and their catalytic activities in the insertion reactions of carbene and nitrene moieties to saturated and unsaturated molecules. The catalytic activity observed with these new complexes is compared to that previously observed with copper(I) complexes with tridentate nitrogen ligands, such as tris(pyrazolyl)borate (Tpx) and tris(pyrazolyl)methane (Tpmx). In the second Chapter, the C-H bond functionalization of indole derivatives with ethyl diazoacetate employing TpxCu(NCMe) complexes as catalysts is described. Additionally, as the reaction takes place through a cyclopropyl indole intermediate, the double functionalization of C2 and C3 positions has consecutively been achieved. The last part of this chapter is devoted to mechanistic studies of this reaction. The third Chapter describes the synthesis and characterization of novel fluorinated imidazolium salts precursors of NHC ligands. Additionally, the preparation of the corresponding copper(I) and gold(I) complexes using these ligands has been carried out. Furthermore, these new gold(l) complexes with fluorinated NHC ligands are used as catalysts in the methane functionalization with ethyl diazoacetate employing scC02 as reaction solvent. The last Chapter studies the catalytic capabilities of NHC-Au(I) complexes in the Mannich addition reactions of 1,3-dicarbonyl compounds with N-protected imines. This Chapter has been written in English to accomplish with the regulation at the University of Huelva to achieve the International Doctorate degree

Coinage metal complexes bearing fluorinated N-Heterocyclic carbene ligands

The synthesis of novel fluorinated symmetrical and unsymmetrical imidazolium salts as well as their corresponding coinage metal complexes is described. The silver derivatives were prepared using Ag2O as the metal source and the subsequent (NHC)AgX complexes were successfully employed in the preparation of the corresponding Cu(I) and Au(I) complexes through transmetallation reactions. Halide extrusion from (NHC)AuCl complexes in the presence of labile ligands also allowed the isolation of Au(I) cationic complexes [(NHC)Au(L)]X. The molecular structures of relevant examples of the neutral and ionic complexes have been unambiguously determined by X-ray studies.The authors thank Agencia Estatal de Investigación (AEI)/FEDER (CTQ2017-82893-C2-1-R, CTQ2016- 75960-P), Red Intecat CTQ2016-81923-REDC, the AGAUR (2017 SGR 1257), and CERCA Program/Generalitat de Catalunya for financial support. M. D. R. thanks the Ministerio de Educación y Ciencia (MEC) for a FPU fellowship and C. G.-M. thanks Agencia Estatal de Investigación for a FPI predoctoral fellowship

Synthesis and catalytic alcohol oxidation and ketone transfer hydrogenation activity of donor-functionalized mesoionic triazolylidene ruthenium(II) complexes

We report on the synthesis of a variety of C,E-bidentate triazolylidene ruthenium complexes that comprise different donor substituents E (E=C: phenyl anion; E=O: carboxylate, alkoxide; E=N: pyridine at heterocyclic carbon or nitrogen). Introduction of these donor functionalities is greatly facilitated by the synthetic versatility of triazoles, and their facile preparation routes. Five different complexes featuring a C,E-coordinated ruthenium center with chloride/cymene spectator ligands and three analogous solvento complexes with MeCN spectator ligands were prepared and evaluated as catalyst precursors for direct base- and oxidant-free alcohol dehydrogenation, and for transfer hydrogenation using basic iPrOH as a source of dihydrogen. In both catalytic reactions, the neutral/mono-cationic complexes with chloride/cymene spectator ligands performed better than the solvento ruthenium complexes. The donor functionality had a further profound impact on catalytic activity. For alcohol dehydrogenation, the C,C-bidentate phenyl-triazolylidene ligand induced highest conversions, while carboxylate or pyridine donor sites gave only moderate activity or none at all. In contrast, transfer hydrogenation is most efficient when a pyridyl donor group is linked to the triazolylidene via the heterocyclic carbon atom, providing turnover frequencies as high as 1400 h-1 for cyclohexanone transfer hydrogenation. The role of the donor group is discussed in mechanistic terms.European Research CouncilScience Foundation Irelan

Synthesis, Structural Characterization, Reactivity, and Catalytic Properties of Copper(I) Complexes with a Series of Tetradentate Tripodal Tris(pyrazolylmethyl)amine Ligands

Novel tris­(pyrazolylmethyl)­amine ligands Tpa^Me3, Tpa*^,Br, and Tpa^Br3 have been synthesized and structurally characterized. The coordination chemistries of these three new tetradentate tripodal ligands and the already known Tpa and Tpa* have been explored using different copper­(I) salts as starting materials. Cationic copper­(I) complexes [Tpa^<i>x</i>Cu]­PF₆ (<b>1</b>–<b>4</b>) have been isolated from the reaction of [Cu­(NCMe)₄]­PF₆ and 1 equiv of the ligand. Complexes <b>2</b> (Tpa^<i>x</i> = Tpa*) and <b>3</b> (Tpa^<i>x</i> = Tpa^Me3) have been characterized by X-ray studies. The former is a 1D helical coordination polymer, and the latter is a tetranuclear helicate. In both structures, the Tpa^<i>x</i> ligand adopts a μ²:κ²:κ¹-coordination mode. However, in solution, all of the four complexes form fluxional species. When CuI is used as the copper­(I) source, neutral compounds <b>5</b>–<b>8</b> have been obtained. Complexes <b>6</b>–<b>8</b> exhibit a 1:1 metal-to-ligand ratio, whereas <b>5</b> presents 2:1 stoichiometry. Its solid-state structure has been determined by X-ray diffraction, revealing its 3D polymeric nature. The polymer is composed by the assembly of [Tpa₂Cu₄I₄] units, in which Cu₄I₄ presents a step-stair structure. The Tpa ligands bridge the Cu₄I₄ clusters, adopting also a μ²:κ²:κ¹-coordination mode. As observed for the cationic derivatives, the NMR spectra of <b>5</b>–<b>8</b> show the equivalence of the three pyrazolyl arms of the ligands in these complexes. The reactivities of cationic copper­(I) derivatives <b>1</b>–<b>4</b> with PPh₃ and CO have been explored. In all cases, 1:1 adducts [Tpa^<i>x</i>CuL]­PF₆ [L = PPh₃ (<b>9</b>–<b>11</b>), CO (<b>12</b>–<b>15</b>)] have been isolated. The crystal structure of [Tpa*Cu­(PPh₃)]­PF₆ (<b>9</b>) has been obtained, showing that the coordination geometry around copper­(I) is trigonal-pyramidal with the apical position occupied by the tertiary amine N atom. The Tpa* ligand binds the Cu center to three of its four N atoms, with one pyrazolyl arm remaining uncoordinated. In solution, the carbonyl adducts <b>13</b>–<b>15</b> exist as a mixture of two isomers; the four- and five-coordinate species can be distinguished by means of their IR ν_CO stretching bands. Finally, the catalytic activities of complexes <b>1</b>–<b>4</b> have been demonstrated in carbene- and nitrene-transfer reactions

Synthesis, Structural Characterization, Reactivity, and Catalytic Properties of Copper(I) Complexes with a Series of Tetradentate Tripodal Tris(pyrazolylmethyl)amine Ligands

Novel tris­(pyrazolylmethyl)­amine ligands Tpa^Me3, Tpa*^,Br, and Tpa^Br3 have been synthesized and structurally characterized. The coordination chemistries of these three new tetradentate tripodal ligands and the already known Tpa and Tpa* have been explored using different copper­(I) salts as starting materials. Cationic copper­(I) complexes [Tpa^<i>x</i>Cu]­PF₆ (<b>1</b>–<b>4</b>) have been isolated from the reaction of [Cu­(NCMe)₄]­PF₆ and 1 equiv of the ligand. Complexes <b>2</b> (Tpa^<i>x</i> = Tpa*) and <b>3</b> (Tpa^<i>x</i> = Tpa^Me3) have been characterized by X-ray studies. The former is a 1D helical coordination polymer, and the latter is a tetranuclear helicate. In both structures, the Tpa^<i>x</i> ligand adopts a μ²:κ²:κ¹-coordination mode. However, in solution, all of the four complexes form fluxional species. When CuI is used as the copper­(I) source, neutral compounds <b>5</b>–<b>8</b> have been obtained. Complexes <b>6</b>–<b>8</b> exhibit a 1:1 metal-to-ligand ratio, whereas <b>5</b> presents 2:1 stoichiometry. Its solid-state structure has been determined by X-ray diffraction, revealing its 3D polymeric nature. The polymer is composed by the assembly of [Tpa₂Cu₄I₄] units, in which Cu₄I₄ presents a step-stair structure. The Tpa ligands bridge the Cu₄I₄ clusters, adopting also a μ²:κ²:κ¹-coordination mode. As observed for the cationic derivatives, the NMR spectra of <b>5</b>–<b>8</b> show the equivalence of the three pyrazolyl arms of the ligands in these complexes. The reactivities of cationic copper­(I) derivatives <b>1</b>–<b>4</b> with PPh₃ and CO have been explored. In all cases, 1:1 adducts [Tpa^<i>x</i>CuL]­PF₆ [L = PPh₃ (<b>9</b>–<b>11</b>), CO (<b>12</b>–<b>15</b>)] have been isolated. The crystal structure of [Tpa*Cu­(PPh₃)]­PF₆ (<b>9</b>) has been obtained, showing that the coordination geometry around copper­(I) is trigonal-pyramidal with the apical position occupied by the tertiary amine N atom. The Tpa* ligand binds the Cu center to three of its four N atoms, with one pyrazolyl arm remaining uncoordinated. In solution, the carbonyl adducts <b>13</b>–<b>15</b> exist as a mixture of two isomers; the four- and five-coordinate species can be distinguished by means of their IR ν_CO stretching bands. Finally, the catalytic activities of complexes <b>1</b>–<b>4</b> have been demonstrated in carbene- and nitrene-transfer reactions