High-valent iron complexes with bispidine ligands: Analysis of spin states and reaction channels

• Applicant: Professor Dr. Peter Comba
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2016 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 282929485

High-valent metal-oxo complexes are relevant in biological systems, in the environment and in processes of industrial importance. With bispidine ligands, we have established and thoroughly studied a platform that enables us to quench and study spectroscopically important intermediates and to vary important parameters such as the coordination geometry, the spin state and the driving force, i.e. the redox potential. We believe that this will enable us to understand how one can switch between specific reaction channels and how important properties (structure, spin, driving force, reactivity) are correlated to each other.An important part of the project is to determine how the driving force and the reactivity depend on the spin state. We believe that we can prepare ferryl systems which at room temperature are close to the spin crossover. We then will determine the redox potential and reactivity at the high-spin (S=2) and intermediate-spin (S=1) states. In addition, we propose systems which should get the so far unknown S=0 state accessible. It will be of great interest to see what redox potential and reactivity such a species has.Another important and not well enough studied point is the basicity of the oxo group. An important species in this context is the tautomer of the metal-oxo-aqua complex, i.e. the dihydroxo complex FeIV(OH)22+ that we have proposed a few years ago and from which we now have preliminary UV-vis-NIR spectra.The experimental studies of our project will be combined with quantum chemical studies done in our group. This combination will allow us to thoroughly interpret the spectroscopic properties as well as thermodynamics and reactivities.

• DFG Programme: Research Grants
• Major Instrumentation: Stopped-Flow Apparatur
• Instrumentation Group: 1120 Spezielle Reaktionsapparaturen (Blitzlicht-, Laser-, Photolyse, Stopped Flow)