Chemistry is undergoing a transformation: moving away from rare precious metals toward sustainable and widely available elements. Researchers like TUM Junior Fellow Dr. Peter Coburger are working precisely at this interface between fundamental research and practical application, with the goal of making catalytic processes more environmentally friendly.

In the recent publication “Modular Design Enables Access to Onium-Substituted Diphosphacyclobutadienyl Complexes”, Coburger’s team presents a new synthetic strategy for innovative ligands in coordination chemistry. The core of the study is a modular “building-block” approach in which reactive ligands are formed directly within the metal complex. This eliminates the often challenging isolation of unstable intermediates. The resulting systems exhibit a zwitterionic structure and show exceptionally strong binding properties toward metals such as manganese and cobalt.

Particularly noteworthy is that these ligand systems are stronger π-donors than classical cyclopentadienyl systems. At the same time, their steric properties can be tuned selectively without altering their electronic characteristics. Another advantage is their reactivity: photochemical methods allow for controlled ligand exchange and the formation of new complexes.

In the following interview, Dr. Peter Coburger provides insights into his career path, his motivation, and the ideas behind his current research.

Could you briefly introduce yourself and your career path?
I completed my Master’s degree in 2015 at Leipzig University. I then pursued my PhD from 2015 to 2019 in the group of Prof. Evamarie Hey-Hawkins, also in Leipzig, where I worked on carborane-substituted diphosphetanes as building blocks for novel phosphorus-based ligand systems. After that, I did a postdoc with Prof. Robert Wolf in Regensburg (2019–2020), focusing more on the theoretical description of unusual metal complexes. I then moved to ETH Zurich to work with Prof. Hansjörg Grützmacher (2020–2022), where I studied the coordination and redox chemistry of biradicaloid ligands. Since 2023, I have been affiliated with the Chair of Inorganic Chemistry with a focus on New Materials led by Prof. Thomas Fässler at the Technical University of Munich, where I head my own research group - initially funded by a Liebig Fellowship and, since 2024, supported by the DFG’s Emmy Noether Programme

What led you to your research topic and what currently drives your work?
My scientific career has been shaped by a wide range of topics—from phosphorus chemistry to theoretical chemistry and coordination chemistry. Initially, my work was driven mainly by a fundamental interest in new compounds. Over time, sustainability became increasingly important to me. Today, I aim to use my experience to make catalytic processes more sustainable. A key area is homogeneous catalysis, where rare precious metals are still widely used. Our goal is to replace these with more abundant elements such as iron, manganese, or cobalt, without compromising efficiency.

What challenges in your field do you find particularly exciting?
One major challenge is replacing precious metals in catalysis. Despite significant progress, precious metals are still often superior, especially in terms of activity and selectivity. For some reactions, such as olefin metathesis, viable alternatives are still lacking. The key lies in tuning the properties of the metal centers, which can be achieved through targeted ligand design. In our group, we develop functionalized π-systems that not only stabilize but also actively participate in reactions. By incorporating phosphorus atoms and charged substituents, we create cooperative ligands that enable new reactivities and can even stabilize otherwise inaccessible metal fragments.

Regarding your publication: what are the key takeaways and future goals?
Until now, there was no general synthetic access to zwitterionic diphosphacyclobutadienyl systems, and we have addressed exactly this gap. My PhD student Stefan Frei developed a modular method that allows these ligands to be synthesized in a building-block fashion. This enables us to fine-tune steric properties while maintaining strong electronic donor characteristics. Using cobalt and manganese complexes, we demonstrated that the concept works and leads to different, complementary reactivity patterns. In the future, we plan to use this platform to systematically study structure–reactivity relationships, for example in hydrophosphination with manganese or olefin reactions with cobalt.

What techniques does your research group use, and are you currently looking for new members?
We combine synthetic chemistry, spectroscopy, theoretical chemistry, and photochemistry. Syntheses are typically carried out under inert conditions using glovebox and Schlenk techniques. For characterization, we use methods such as NMR spectroscopy, X-ray crystallography, and mass spectrometry. A key component of our work is theoretical modeling, which helps us understand reactivity and predict new systems. We also use light to selectively trigger reactions, for example for ligand exchange processes. We are currently looking for students, particularly for Master’s projects in the area of the catalytic activation of small molecules such as hydrogen or carbon dioxide with manganese complexes.

Publication

Modular Design Enables Access to Onium-Substituted Diphosphacyclobutadienyl Complexes, ChemistryEurope, https://chemistry-europe.onlinelibrary.wiley.com/doi/epdf/10.1002/ceur.202500475

Further information

• Peter Coburger, Phosphorheterozyklen für nachhaltige Katalyse
• ChemistryViews article: https://www.chemistryviews.org/building-zwitterionic-phosphorus-analogues-of-cyclobutadienyl-ligands-within-the-metal-coordination-sphere/. Here, Dr. Peter Coburger reports in ChemistryViews on the construction and investigation of zwitterionic phosphorus analogues of cyclobutadienyl ligands within the metal coordination sphere, as well as their electronic structure and bonding properties.

Press contact
communications@nat.tum.de 
Team Website