Dissertation

|2 Scope of the Thesis|
motifs with high synthetic flexibility and tunable electronic properties shall be generated, applied
and tested. Important is the good stabilization of P and C at the bridge, therefore, old bridging
concepts shall be advanced and new donor functionalities shall be introduced into the binding
sites. This will additionally allow for the application of new catalytically active metals, to overcome
the drawbacks of the first generation catalysts. In this respect, especially the easy to functionalize
phenanthroline derivatives are of interest, as they can be extended by a second coordination sphere
e.g. by a NHC moiety.
Furthermore, the electron storage/mediating capacity of the bridge is important, thus, different
bridging concepts (conjugated/isolated systems) shall be developed and applied to optimize
the electronic communication across the bridge. The introduction of different groups at the
bridge shall be applied to generate an electronic situation that localizes the excited electron
predominantly on the bridge.
With respect to the catalytic center, a number of different metals, e.g. the previously used platinide
metals such as Rh, Re, Pd or Pt shall be applied, but also new metals with a better availability such
as Co, Fe or Ni shall be considered. A comparison within a series of similar catalysts can be used
to increase the efficiency of the system.
With a complete P ∼ B ∼ C-system in hands, using the established methods from the workgroup
of Rau, detailed catalytic (screening)experiments shall be performed to test their activity in the
light driven hydrogen production and to advance the systems in the future.
Toward these new P ∼ B ∼ C-systems, at first, new methods for the preparation of the new
ligands shall be developed and applied. The intermediately obtained ligands shall be analyzed
and characterized. Furthermore, a number of new ruthenium complexes with these ligands shall
be generated and characterized. Using the prepared ruthenium complexes, particularly those
containing bridging ligands, as starting materials, additional catalyst centers shall be attached
to obtain suitable P ∼ B ∼ C-model systems. In this way different series of ruthenium and
ruthenium/catalyst metal complexes, varying in ligand parameters or catalyst parameters shall
be prepared. Especially with the help of different spectroscopic and electrochemical experiments,
using the mono- and oligo-nuclear complexes, detailed insights into the electronic behavior of the
ground and excited state molecules shall be obtained. With respect to the performed changes and
in the scope of an application in catalysis, structure-property relationships shall be revealed.
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