PEPPSI-type Complexes of Palladium and Platinum: : Investigation of Properties and Applications in Catalysis

Sammanfattning: Catalysis is a powerful tool to highly efficient production of desired newchemicals by acceleration of a chemical reaction rate. Special compounds used forthis purpose are called catalysts; they induce a change in the chemicalenvironment without being consumed during the process. Catalysis affects manyfields of life leading to a decrease of the energy use, less pollution, fewer sideproducts and lower starting materials cost.The broad variety of the catalysts can be divided into two major types –homogeneous, that are in the same phase as the reaction mixture, andheterogeneous, which are presented in a different phase than the reactants. Bothgroups have their own advantages as well as drawbacks. Researchers worldwideput a lot of efforts in creating of the so-called ideal catalyst that will combinepositive features of both kinds of catalytic systems: the high selectivity andactivity of homogeneous catalysts with recyclability and ease of separation forheterogeneous ones. A promising candidate for such a title is a supportedhomogeneous catalyst where a metal complex is anchored by chemical bonding toa suitable support that can be inorganic oxide, zeolites, organic polymers or carbonnanotubes.Among the myriads of chemical processes the direct conversion of unreactive rawmaterials, such as hydrocarbons, to functional molecules containing diversefunctionalities such as halogen, nitro, acetoxy, alkyl or aryl groups is highlydesirable. The main challenge here is to break a very strong carbon-hydrogen(C−H) bond to replace the hydrogen with a desired functional group. Anotherproblem is the selectivity of the process as the molecule of the reactant oftencontains a number of C−H bonds with the same reactivity. These issues can beovercome with the help of transition-metal catalysis: a metal center can coordinatethe starting material forming an intermediate complex that will selectively delivera functional group to a proximal position in the molecule. This transformation isalso known as a C−H bond activation.N-heterocyclic carbene (NHC) complexes with transition metals are a fascinatingclass of compounds where the strong bond between the carbon atom of the carbeneligand and the metal center is the reason for its high stability. These compoundsfind application across the chemical field including their use in materials, asmetallopharmaceuticals and as homogeneous catalysts, showing great catalyticactivity in a range of reactions.Therefore in the present thesis we decided to investigate and discuss the followingtopics: development and catalytic activity of a novel platinum-NHC complex of aPEPPSI type, application of palladium NHC complexes to a selective liganddirectedC−H bond acetoxylation, development of approaches for immobilizationof the palladium-N-heterocyclic carbene complexes on mesoporous silica support,application of supported palladium-NHC complexes in C−H bond activationcatalysis and characterization of the functionalized materials.