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@PHDTHESIS{Meuresch:660256,
author = {Meuresch, Markus},
othercontributors = {Klankermayer, Jürgen and Leitner, Walter},
title = {{M}aßgeschneiderte {R}uthenium-{T}riphos {K}atalysatoren
für die homogenkatalysierte {H}ydrierung von
{C}arbonsäurederivaten},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
reportid = {RWTH-2016-05261},
pages = {1 Online-Ressource (146 Seiten) : Illustrationen,
Diagramme},
year = {2016},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2016},
abstract = {The present thesis deals with the development of
tailor-made ruthenium catalysts for the selective conversion
of carboxylic acids, esters and amides, based on the
[Ru(Triphos)TMM] catalyst lead structure (TMM =
trimethylenemethane, Triphos =
1,1,1-tris(diphenylphosphinomethyl)ethan).Chapter 1
describes the state-of-the-art in hydrogenation with
molecular catalysts and the importance of catalytic
reduction as a tool for the chemical transformation of polar
bonds in laboratory as well as in industrial scale. The
[Ru(Triphos)TMM] complex is a universal catalyst for the
catalytic conversion of carboxylic acid derivatives, for the
di-rect hydrogenation of CO2 to methanol, as well as for the
direct methylation of aromatic amines using CO2 as a C1
building block. However, mechanistic investigations revealed
that the catalyst deactivates irreversibly by forming an
inactive ruthenium dimer in all catalytic transformations,
thus preventing a general applicability.In order to prevent
the catalyst from deactivating via dimerization, the ligand
was chemically modified as described in chapter 2. The dimer
formation should be blocked by the introduction of
sterically demanding substituents to the aromatic backbone
of the ligand, for this reason, a library of 7 triphos
derivatives and their corresponding ruthenium complexes
could be established. The molecular structures from
single-crystal x-ray diffraction of the complexes emphasized
that the meta-substituents of the newly developed Triphos
Xyl (1,1,1-tris(3,5-dimethylphenylphosphinomethyl)ethan)
showed a significantly increased shielding of the ruthenium
center in comparison to the usual triphos ligand, paving the
way for application in challenging reductive
transfor-mations. Chapter 3 contains the detailed
mechanistic characterization of the different catalyst
species. The activation of [Ru(Triphos)TMM] in the presence
of hydrogen leads to the formation of the hydride complex
[Ru(Triphos)(H)2], the cationic complex
[Ru(Triphos)(H)(H2)][NTf2] is formed in the presence of
HNTf2. Moreover, the XRD-analysis of a ruthenium dimer
showed that the meta-substituents of the Triphos Xyl ligand
should have a major influence on the dimer formation. In
selected catalytic reactions (chapter 4) the novel catalyst
demonstrated remarkable activities in the hydrogenation of
carboxylic acids, esters and amides. Moreover, it was shown
by NMR-analysis that the dimer formation was completely
prevented in a cata-lytic reaction by the introduction of
the Triphos-Xyl ligand. Thus, the Triphos-Xyl ligand
significantly improves the chemical stability, catalytic
activity and selectivity in the hydrogenation of dimethyl
itaconate, itaconic acid and N-acetanilide.},
cin = {154320 / 154110 / 150000},
ddc = {540},
cid = {$I:(DE-82)154320_20160617$ / $I:(DE-82)154110_20140620$ /
$I:(DE-82)150000_20140620$},
typ = {PUB:(DE-HGF)11},
urn = {urn:nbn:de:hbz:82-rwth-2016-052614},
url = {https://publications.rwth-aachen.de/record/660256},
}
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