Synthesis and characterization of Ruthenium polypyridyl complexes for alkene epoxidation catalysis

Abstract

In this dissertation work we have developed and optimized a synthetic route to obtain different ruthenium complexes with N-donor type ligands, afterwards, we have evaluated the efficiency of an aqua-complex as catalyst for the epoxidation of alkenes. Initially we have synthesized one of the non-commercial N-donor ligand (pypz-H), and the starting product cis,cis-[RuCl2(dmso)2(pypz-H)] 2, this mononuclear complex reacts further with the ligand trpy to generate a mixture of the chloro-complex cis, trans[RuCl(trpy)(pypz-H)](PF6) 3b and 3a. Afterwards, from this one we have synthesized and characterized the correspondent aqua-complex trans-[Ru(trpy)(pypzH)(OH2)](PF6)2 4a. All the compounds have been characterized in solution throught spectroscopic techniques (RMN, UV-Visible) and some of them by X-ray difraction, confirming that they maintain their structure in solid state. The redox properties of the compounds have been studied by CV and DPV. The Pourbaix diagram displayed by the complex trans-[Ru(trpy)(pypz-H)(OH2)](PF6)2 4a allowed to obtain data about the redox equilibriums as well as have allowed to know the correspondent pKa values of the RuII and RuIII species. Finally, we have evaluated the catalytic activity of the complex trans-[Ru(trpy)(pypzH)(OH2)](PF6)2 4a in the alkene epoxidation, using PhI(OAc)2 as oxidant. The results obtained shown good conversion values for the compounds tested as well as excellent selectivity values