Please use this identifier to cite or link to this item: https://scholarbank.nus.edu.sg/handle/10635/135301
Title: RUTHENIUM (II) COMPLEXES WITH N-HETEROCYCLIC CARBENE LIGANDS: STRUCTURE AND CATALYTICAL STUDIES
Authors: XIE XIAOKE
Keywords: Ruthenium, N-heterocyclic carbene, catalysis, dehydrogenation, amination and amination, C-H activation
Issue Date: 18-Aug-2016
Citation: XIE XIAOKE (2016-08-18). RUTHENIUM (II) COMPLEXES WITH N-HETEROCYCLIC CARBENE LIGANDS: STRUCTURE AND CATALYTICAL STUDIES. ScholarBank@NUS Repository.
Abstract: This dissertation reports the N-heterocyclic carbene (NHC) chemistry of ruthenium(II), and the findings are discussed in three chapters. Chapter 2 focus on the synthesis and characterization of three simple air and moisture stable ruthenium-NHC complexes.These complexes were found to be efficient catalysts for the alkylation of amines using alcohols as alkylating agents. In addition, two mixed NHC/phosphine complexes have been synthesized and fully characterized. They are able to selectively catalyze both dehydrogenative amidation, mono- and di-amination (N-alkylation) through coupling of simple alcohols with amines effectively yielding a range of amides, secondary and tertiary amines. Selectivity is achieved by controlling the fate of the common hemiaminal intermediate, which in turn can be simply influenced by the choice of base and solvent. In chapter 3, the catalytic dehydrogenative amidation and amination through coupling of alcohols with other nitrogen containing species are discussed. Complex 83 turns out to be the suitable catalyst for the amidation through alcohols with nitriles and the mono- and di- amination through the coupling of alcohols with nitro arenes. Various amides, secondary and tertiary amines can be synthesized using this methodology. A series of six [RuX(2-thienyl-NHC)(p-cymene)] complexes have been prepared via NHC directed C-H activation in Chapter 4. All complexes have been fully characterized.The rotational barrier of the N-benzyl substituent in the bromido complex 153b has been measured by variable temperature 1H NMR spectroscopy. Preliminary reactivity studies of complex 156 with alkynes provided four new annulated aza-heterocyclic thiophenes.
URI: http://scholarbank.nus.edu.sg/handle/10635/135301
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