Efecto de la estructura química en compuestos de coordinación con ligantes polipiridínicos en la catálisis molecular de dióxido de carbono

• Autores: Juan Pablo Francisco Rebolledo Chavez
• Directores de la Tesis: Luis Antonio Ortiz Frade (dir. tes.)
• Lectura: En la Centro de Investigación y Desarrollo Tecnológico en Electroquímica ( México ) en 2021
• Idioma: español
• Enlaces
  • Tesis en acceso abierto en: cideteq.repositorioinstitucional.mx
• Resumen
  • español

    En el presente trabajo se sintetizaron y caracterizaron compuestos de coordinación con ligantes polipiridínicos de CoII [CoII(L)3](BF4)2, [CoII(L´)2](BF4)2 y de NiII con un ligante tetradentado flexible polipiridínico [NiII(tpa)(H2O)(MeCN)](BF4)2, [NiII(tpa)(NO3)2] y [NiII(tpa)Cl2] con la finalidad de explorar el efecto del potencial redox, la estructura molecular y electrónica de compuestos de coordinación, en la capacidad de la reducción electroquímica del CO2.

  • English

    In the present work, coordination compounds with polypyridine ligands of CoII [CoII(L)3](BF4)2 and [CoII(L´)2](BF4)2 (L = 2,2'- bipyridine, 1,10- phenanthroline, 3,4,7,8tetramethyl-1,10-phenanthroline, 5,6-dimethyl-1,10-phenanthroline, 4,7-diphenyl-1,10phenanthroline; L'= terpyridine, 4-Chloro-terpyridine) and NiII with a flexible polypyridine tetradentate ligand (tpa = tris (2-pyridyl methylamine), [NiII(tpa)(H2O)(MeCN)](BF4)2, [NiII(tpa)(NO3)2] and [NiII(tpa)Cl2] were synthesized and characterized, in order to explore the effect of redox potential, molecular and electronic structure of coordination compounds on the ability of the electrochemical reduction of CO2 was studied. The electrochemical response in the presence and absence of carbon dioxide, employing acetonitrile as a dissolvent. In addition, the results are supported by computational calculations. In the tris [CoII(L)3](BF4)2 and bis [CoII(L´)2](BF4)2 chelate CoII complexes, it was found that as the redox potential is more negative and there is no coupled chemical reaction, the value of the CO2 reduction constant (k) increases. In this way, [Co(3,4,7,8-tm-1,10-phen)3]2+ presented the highest k value (2.40x103 M-1 s-1). Theoretical calculations give a reliable description for the electronic distribution of the chemical species generated in the reduction of [CoII(L)3]2+ and [Co(L´)2]2+ complexes. NiII(tpa) family of complexes presented tunable redox potential from -1.464 to -1.794 V vs Fc-Fc+ for the NiII/NiI reduction. The reduced form of [NiII(tpa)(H2O)(MeCN)](BF4)2 complex, a change from octahedral geometry to a square planar pyramidal geometry was proven by spectroelectrochemistry, crystal field theory, and computational calculations. The NiII complexes that exhibit the more negative redox potential are those that have higher catalytic activity for CO2 reduction. Likewise, the reduced form of [NiII(bipy)3](BF4)2, activates the CO2 molecule at a lower potential.