Synthesis of new RU(II) complexes as catalysts for nitrile hydration and alkene epoxidation

Abstract

During this experience in the research group in the synthesis of ruthenium complexes with N-Donor ligands and their application in catalysis, in this work we have developed different pathways to obtain new ruthenium complexes using N-Donor ligands that have been and subsequently evaluated as catalysts for the hydrolysis of nitriles and alkene epoxidation. Initially, a N-donor ligand non-commercial (pypzH) has been synthesized and, using in all cases ligand terpyridine, it has been possible to obtain the starting material ([RuCl2(dmso)2(pypzH)], [RuCl3(trpy)] and [RuCl2(dmso)(trpy)], and it has been developed three different pathways for the formation of the ruthenium complex of interest ([RuCl(trpy)(pypzH)](PF6)). The complex has been characterized using different spectroscopic and electrochemical techniques. Afterwards, from this chlorocomplexes it has been synthesized and characterized the corresponding aquacomplex [Ru(trpy)(pypzH)(OH2)](PF6)2. About structural characterization, the formation of a single isomer for [RuCl2(dmso)2(pypzH)] was obtained, while the [RuCl2(dmso)(trpy)] complex was obtained a mixture of isomers which is clearly seen in NMR spectrum. Note that for [RuCl(trpy)(pypzH)](PF6) complex was also obtained two isomers, cis and trans, but it had been purified only the trans isomer by column chromatography. UV-Vis spectra have been performed in dichloromethane for the complex [RuCl(trpy)(pypzH)](PF6), where the presence of MLCT and intraligand -* bands is a clear evidenced in the complex. In addition, it has performed a spectrophotometric assay to confirm the aquacomplex [Ru(trpy)(pypzH)(OH2)](PF6)2 formation, where you can see the movement of the bands in front of pH variations of the aqueous medium in which the spectra are recorded. The complex [RuCl(trpy)(pypzH)](PF6) was also characterized by electrochemical techniques where a reversible wave corresponding to the Ru(III/II) redox pair have been observed. For aquacomplex [Ru(trpy)(pypzH)(OH2)](PF6)2, the cyclic voltammetry was shown two waves corresponding to Ru(IV/III) and Ru(III/II) pares which was varying the potential value versus pH. Finally, the catalytic activity the hydrolysis of nitriles and epoxidation of alkenes, of the complex [RuCl(trpy)(pypzH)](PF6) has been evaluated using two different substrates. The results obtained of both catalysis, are reasonably good or good in terms of conversions and excellent in the case of selectivity