Research Area B: Synthesis and Catalysis
Quantum Chemical Investigations on the Function of Different Metal Atoms in Transition Metal Catalysed Reactions
Project B1 has two subtopics. One aim of this project is the coordination of the quantum chemical calculations in the B-projects of the SFB/TRR. Here, project B1 shall assist the other projects in realization of the quantum chemical calculations. The main goal of subproject B1 is the analysis of the role of different metal centres in transition metal catalysed reactions. The metal centres shall be varied systematically and the bonding situation at the metal centres is going to be investigated. Of special interest is the role of the open d or f-shells. For this purpose simplified model systems will be constructed which will then be treated with highly accurate wavefunction based methods.
Heterodinuclear Complexes Combining Electron-Rich Transition Metals and Hard Lewis Acids
The interaction of late, electron-rich transition metals and hard Lewis acids, which are located in typical 3MET complexes in close proximity to each other, had rather poorly been investigated in relation to catalysis. For this intention, ligands have to be synthesized, which will keep the metal centres in a well defined structural relationship. It’s the aim of this project to synthesize and characterize 3MET complexes possessing an electron-rich, late as well as an electron-poor, early transition metal or lanthanide ion and to investigate their collaboration in catalysis.
Homodinuclear Lanthanide Complexes and Heterodinuclear Lanthanide-d-Metal Complexes
The aim of the project is the synthesis of bimetallic complexes as catalysts for the transformations of C-C multiple bonds. The main focus lays on the hydroamination but other transformation such as the catalytic hydrosilylation will also be investigated. As target complexes we plan to synthesize homo dinuclear complexes of the lanthanides first, followed by the synthesis of hetero dinuclear complexes of the lanthanides and the platinum metals as well as of the lanthanides and 3d metals. As ligand backbone polycyclic aromatic compounds will be mainly employed.
Di- and Trinuclear Transition Metal Complexes Consisting of Multidentate Ligands and their Application in Homogeneous Catalysis
The main goal of the project aims the synthesis of di- and trinuclear transition metal complexes and their application in homogeneous catalysis. These complexes consist of either direct or none M-M bonds. The metal metal distances and combinations as well as the electronic interactions between them will be systematically modified by applying tailored chelating ligands. Catalytic studies will mainly focus on C-C coupling and hydroamination reactions using late transition metals. Particularly, the well-directed variation of the metals, the precise adjustment of the electronic properties and the elucidation of the key steps in catalysis will be of interest.
B5: Paradies (till 2015, now U Paderborn)
Bimetallic Systems for C-C and C-X-Bond Formation
The aim of the project is the synthesis of heterobimetallic complexes and their application in catalytic C-C- and C-X-bond forming reactions. From this broad variety of reactions the focus is directed to the hydroamination and the Sonogashira cross-coupling reaction. Heterobimetallic complexes, which are suitable for these reactions bear gold/zinc or gold/lanthanoid or palladium/copper or nickel/copper metal atoms for the activation of substrates. The spatial distance of the two metal atoms will be modulated by a rigid ligand backbone based on the [2.2]paracyclophane framework. For the selective complexation of the metal atoms the differing donor affinities will be exploited.
B6: Gooßen/Niedner-Schatteburg (till 2018)
Mechanistic Studies on Bimetallic Reactions: Hydroaminations and Sonogashira Couplings
It is the goal of this project to investigate the cooperativity of metal centers in homogeneous processes catalyzed by bimetallic systems. With the help of spectroscopic investigations (ESI-MS, NMR, IR) and model studies, we aim to find evidence for the theory that many reactions, which are presently believed to involve direct ligand exchange steps between the metals, in fact proceed via the formation of structurally defined bimetallic intermediates. In the focus of our investigations will be Sonogashira couplings and decarboxylative cross-couplings catalyzed by Pd/ Ag or Cu as well as hydroaminations of multiple bonds catalyzed by lanthanide-Ru systems.
B7: Patureau (till 2018)
The aim of this project is to prepare homo and hetero dinuclear transition metal complexes, and to apply the resulting defined organometallic species as catalysts in cross-dehydrogenative-coupling (CDC) amination reactions. The ligands are made of three tethered parts: 1) an electron-rich p-arene system, 2) a carboxylate moiety, and 3) a covalent organic linker between the two. For aromatic amination reactions one single metal alone cannot achieve such a reactivity. We expect the developed cooperative polynuclear catalysts to improve significantly the scope of CDC-amination reactions.
Multinuclear d-block metal complexes for catalysis of multi-electron redox reactions
This 3MET project synthesizes, characterizes, and spectroscopically investigates multinuclear d-block metal complexes with macrocyclic complexes as well as catalytic multielectron transfer reactions. It seeks to achieve functional cooperativity by µ4-oxido copper clusters ([Cu4OCl6L4], L = ligand) which couple to Fe(III) porphyrin complexes. It focusses on their catalytic oxidation and selective hydroxylation reactions. The project sees a necessity to correlate the structural features and ligand effects with electronic properties in order to gain a deeper understanding of the cooperative effects which arise from the coupling of the metal centers.
Multinuclear Transition Metal Complexes for the Photocatalytic Reduction of Carbon Dioxide
This 3MET project synthesizes and characterizes new di- and trinuclear transition metal complexes for artificial photosynthesis, and it evaluate their activity in the photocatalytic reduction of carbon dioxide. It focusses on multinuclear metal complexes based on earth-abundant metals, such as copper, zinc, iron, cobalt or nickel. It designs bridging ligands by modifying the chelating units and the linker moiety to modulate elec-tronic interactions. It investigates cooperative effects of the metal cores in order to engineer the excited states, the photophysical and the electrochemical properties of the new 3MET complexes.
Mechanistic Studies of Reactions Catalyzed by Bi- and Trimetallic Complexes
This 3MET project aims to discover new reactivities induced by the cooperative action of multimetallic homogeneous catalysts. It investigates reactions that were confirmed to involve bimetallic transition metal complexes. It sets a focus on bimetallic complexes with metal centers in unusual oxidation states, e.g. Pd(I) and Rh(II). It establishes structure-activity relationships for metallic cores and bridging ligand systems whenever unique reactivity of the bimetallic species arises. It uses stoichiometric experiments and catalytic screening in combination with DFT investigations and kinetic studies. It rationally turns multimetallic adducts with unusual catalytic reactivity into practical catalysts with high durability and activity.