PEPPSI-type Complexes of Palladium and Platinum: : Investigation of Properties and Applications in Catalysis
Author
Summary, in English
Catalysis is a powerful tool to highly efficient production of desired new
chemicals by acceleration of a chemical reaction rate. Special compounds used for
this purpose are called catalysts; they induce a change in the chemical
environment without being consumed during the process. Catalysis affects many
fields of life leading to a decrease of the energy use, less pollution, fewer side
products 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, and
heterogeneous, which are presented in a different phase than the reactants. Both
groups have their own advantages as well as drawbacks. Researchers worldwide
put a lot of efforts in creating of the so-called ideal catalyst that will combine
positive features of both kinds of catalytic systems: the high selectivity and
activity of homogeneous catalysts with recyclability and ease of separation for
heterogeneous ones. A promising candidate for such a title is a supported
homogeneous catalyst where a metal complex is anchored by chemical bonding to
a suitable support that can be inorganic oxide, zeolites, organic polymers or carbon
nanotubes.
Among the myriads of chemical processes the direct conversion of unreactive raw
materials, such as hydrocarbons, to functional molecules containing diverse
functionalities such as halogen, nitro, acetoxy, alkyl or aryl groups is highly
desirable. The main challenge here is to break a very strong carbon-hydrogen
(C−H) bond to replace the hydrogen with a desired functional group. Another
problem is the selectivity of the process as the molecule of the reactant often
contains a number of C−H bonds with the same reactivity. These issues can be
overcome with the help of transition-metal catalysis: a metal center can coordinate
the starting material forming an intermediate complex that will selectively deliver
a functional group to a proximal position in the molecule. This transformation is
also known as a C−H bond activation.
N-heterocyclic carbene (NHC) complexes with transition metals are a fascinating
class of compounds where the strong bond between the carbon atom of the carbene
ligand and the metal center is the reason for its high stability. These compounds
find application across the chemical field including their use in materials, as
metallopharmaceuticals and as homogeneous catalysts, showing great catalytic
activity in a range of reactions.
Therefore in the present thesis we decided to investigate and discuss the following
topics: development and catalytic activity of a novel platinum-NHC complex of a
PEPPSI type, application of palladium NHC complexes to a selective liganddirected
C−H bond acetoxylation, development of approaches for immobilization
of the palladium-N-heterocyclic carbene complexes on mesoporous silica support,
application of supported palladium-NHC complexes in C−H bond activation
catalysis and characterization of the functionalized materials.
chemicals by acceleration of a chemical reaction rate. Special compounds used for
this purpose are called catalysts; they induce a change in the chemical
environment without being consumed during the process. Catalysis affects many
fields of life leading to a decrease of the energy use, less pollution, fewer side
products 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, and
heterogeneous, which are presented in a different phase than the reactants. Both
groups have their own advantages as well as drawbacks. Researchers worldwide
put a lot of efforts in creating of the so-called ideal catalyst that will combine
positive features of both kinds of catalytic systems: the high selectivity and
activity of homogeneous catalysts with recyclability and ease of separation for
heterogeneous ones. A promising candidate for such a title is a supported
homogeneous catalyst where a metal complex is anchored by chemical bonding to
a suitable support that can be inorganic oxide, zeolites, organic polymers or carbon
nanotubes.
Among the myriads of chemical processes the direct conversion of unreactive raw
materials, such as hydrocarbons, to functional molecules containing diverse
functionalities such as halogen, nitro, acetoxy, alkyl or aryl groups is highly
desirable. The main challenge here is to break a very strong carbon-hydrogen
(C−H) bond to replace the hydrogen with a desired functional group. Another
problem is the selectivity of the process as the molecule of the reactant often
contains a number of C−H bonds with the same reactivity. These issues can be
overcome with the help of transition-metal catalysis: a metal center can coordinate
the starting material forming an intermediate complex that will selectively deliver
a functional group to a proximal position in the molecule. This transformation is
also known as a C−H bond activation.
N-heterocyclic carbene (NHC) complexes with transition metals are a fascinating
class of compounds where the strong bond between the carbon atom of the carbene
ligand and the metal center is the reason for its high stability. These compounds
find application across the chemical field including their use in materials, as
metallopharmaceuticals and as homogeneous catalysts, showing great catalytic
activity in a range of reactions.
Therefore in the present thesis we decided to investigate and discuss the following
topics: development and catalytic activity of a novel platinum-NHC complex of a
PEPPSI type, application of palladium NHC complexes to a selective liganddirected
C−H bond acetoxylation, development of approaches for immobilization
of the palladium-N-heterocyclic carbene complexes on mesoporous silica support,
application of supported palladium-NHC complexes in C−H bond activation
catalysis and characterization of the functionalized materials.
Department/s
Publishing year
2016-08
Language
English
Document type
Dissertation
Publisher
Lund University, Faculty of Science, Department of Chemistry, Centre for Analysis and Synthesis
Topic
- Organic Chemistry
Keywords
- PEPPSY-type complexes
- palladium
- platinum
- C−H activation
- supported homogeneous catalysts
Status
Published
Supervisor
ISBN/ISSN/Other
- ISBN: 978-91-7422-471-9
Defence date
22 September 2016
Defence time
09:15
Defence place
Center for chemistry and chemical engineering, lecture hall C, Naturvetarvägen 14, Lund
Opponent
- Freddy Kleitz (Professor)