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A Redox-Switchable Germylene and its Ligating Properties in Selected Transition Metal Complexes
Florian Walz1, Eric Moos1, Delphine Garnier1,2
1Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstr. 15, 76131, Karlsruhe, Germany.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|November 25, 2016
Summary
This study presents a redox-switchable germylene ligand, [Fc(NMes)2Ge], which forms stable complexes with molybdenum and tungsten. Its electronic properties change significantly upon oxidation, impacting metal-ligand interactions.
Area of Science:
- Organometallic Chemistry
- Main Group Chemistry
- Coordination Chemistry
Background:
- Ferrocenophanes are versatile ligands in organometallic chemistry.
- Redox-switchable ligands offer tunable electronic properties for catalysis and materials science.
- Germylenes, divalent germanium compounds, are increasingly explored as ligand motifs.
Purpose of the Study:
- To synthesize and characterize a novel redox-switchable germylene based on a ferrocenophane scaffold.
- To investigate the coordination behavior of the germylene with transition metals.
- To elucidate the electronic changes and bonding characteristics upon oxidation of metal-germylene complexes.
Main Methods:
- Synthesis of the germylene [Fc(NMes)2Ge] from ferrocenophane precursors.
- Characterization using cyclic voltammetry, NMR spectroscopy, and X-ray diffraction.
- Density Functional Theory (DFT) calculations to study electronic structures and bonding.
Main Results:
- Successful synthesis and full characterization of the redox-switchable germylene [Fc(NMes)2Ge].
- Isolation and characterization of stable complexes with molybdenum and tungsten, [Mo(κ1Ge-4)2(CO)4] and [W(κ1Ge-4)2(CO)4].
- DFT calculations reveal significant changes in ligand-donating abilities and Tolman electronic parameter (TEP) upon oxidation, primarily due to Coulombic effects.
Conclusions:
- The synthesized germylene functions as a redox-switchable metalloligand.
- While Rh(I) and Ir(I) complexes were unstable, Mo and W complexes demonstrated good stability.
- Oxidation of the ferrocene unit in the metalloligand significantly alters its electronic properties, influencing metal-ligand interactions.
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