DUGi

Preparació i caracterització de complexos de ruteni amb aplicació a la catàlisi d’acoblament d’alcohols en condicions tèrmiques i fotoactivades

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@26229

Throughout this study, the synthesis of a set of ruthenium complexes has been carried out with the aim of coordinating different types of ruthenium ligands. The aim of these synthesised complexes is to use them for the catalysis of alcohol assembly reactions. Firstly, the ligand bpea (N,N-bis(2-pyridylmethyl)ethylamine) and the complex [1], [RuCl2(dmso)4], have been synthesised and used to obtain the complex [2] (cis,fac- [RuCl2(bpea)(dmso)]). The complex [3], [RuCl3(bpea)], . has been prepared from RuCl3 and the same bpea ligand. A second ligand, 3-methyl-1-(pyridin-2-yl)-1H-imidazol-3- yum-hexafluorophosphate (HCb-Me(PF6)), has also been synthesised and reacted with complex [3] to give complex [4], (trans,fac-[RuCl(Cb-Me)(bpea)]). The bpea and HCb-Me(PF6) ligands have been characterised by 1H-RMN, while other spectroscopic and electrochemical techniques such as UV-Visible and cyclic voltammetry have been used for the [1]-[4] complexes. In the case of complexes [2] and [4], the analysis by 1H-RMN has allowed us to determine that they are obtained as single isomers, cis,fac- and trans,fac- respectively. The complexes [2] and [4] show, in the UV-vis spectra, charge transfer metal-lligand (TCML) bands, as well as intralligand π-π* transitions. An effect of the dmso ligands on the energy of the TCML transitions can be observed, which are more energetic for the complex [2], which contains this π-acceptor ligand.Cyclic voltammetry of the [2]-[4] complexes shows reversible waves corresponding to the RuIII/RuII redox pair, which has a particularly low E1/2 potential value in the case of the [3] complex, as it has three chloride ligands in the coordination environment. Catalysis tests on the alcohol assembly reaction have been performed with the complexes [2] and [4] under thermal (80ºC) and also photoactivated (applying visible light) conditions. The quantification of the catalysis products has been performed by gas chromatography with FID detector and, in the case of complex [4], some evolution and quantification controls have also been performed by 1H-RMN. Conversion and selectivity values have been obtained that allow us to see the efficiency of the catalysts over 1, 3, 5 and 7 days, and it has been observed that, while the complex [2] shows practically no catalytic activity, the complex [4] proves to be efficient in the tests carried out under temperature

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