Siegel der Universität zu Köln
University of Cologne
Faculty of Mathematics and Natural Sciences
Department of Chemistry - Inorganic Chemistry


Research Areas: coordination chemistry, transition metals, bioinorganic chemistry, spectroscopy

Scientific Aims:
The centre of our scientific work lies in the preparation and investigation of novel coordination compounds (complexes) including organometallic derivatives. Our aim is the rational design, preparation and use of coordination units (complex fragments) with specific properties (functions) in mononuclear or oligonuclear complexes or as part of materials.
The specific properties e.g. reactivity in the ligand sphere, activation of ligands, redox chemistry on metal or ligand, electron transfer, luminescence, photochemistry, stable radicals, magnetism etc. determine the potential applications of such materials.
Variation of metals and design of ligands enable us to draw correlations between molecular structure and physical or chemical properties of the coordination units.

Fig. 1: Binding of biomolecules to platinum:
molecular structure of [Pt(Me)(COD)(cytosine)]+ (COD) = 1,5-cyclooctadiene); the cytosine H2N(4) exhibits a medium strong hydrogen bond to H2O in the crystal

Potential applications:

Fig. 2: Photochemistry:
absorption spectra of [Pt(tBuC≡C)2(COD)] during irradiation; under irradiation the compound undergoes a clean reductive elimination reaction leading to platinum particles.

All syntheses and investigations can be carried out under an inert atmosphere (Schlenk technique or glove box) including low-temperature conditions (cooling baths, cryostats). Analytical or spectroscopic methods are single crystal XRD, EXAFS (in cooperation); electrochemistry; photochemistry; absorption- (UV/vis/NIR) or emission spectroscopy (partly in cooperation); IR-, Raman- or resonance Raman spectroscopy; EPR spectroscopy; spectroelectrochemical methods (EPR, UV/vis/NIR, IR); and quantum chemical calculations (in cooperation). Gas phase chemical investigation of small reactive molecules (generation by pyrolysis, RF discharge or laser ablation as well as detection by MS or IR- or Terahertz spectroscopy) in cooperation with 1. Physikalisches Institut.

Fig. 3: Electrochemical activation:
cyclic voltammogramms of [NiBr(Mes)(bpy)] at various conditions (to the left); prolonged electrolysis leads to the stable radical [Ni(Mes)2(bpy)]•- (X-Band EPR spectrum, to the right)

Present projects: