Research Interests

Recycling of Rare Earth Elements

Recycling  During the past twenty years rare-earth-based materials and compounds have become increasingly important to all aspects of the technologies that underpin modern-day life. However, the main post-consumer activities - the recycling of rare earths - have not been developed in that time. Up to now, there has been no large-scale recycling of rare earths from magnets, batteries, lighting and catalysts. Therefore, we are looking for chemical and technological solutions which would enable the isolation and separation of rare earth metal ions from process leach solutions accrue in the recycling process of rare-earth-based materials.

Chemistry of Metallacyclic Alkylidene Complexes

High-oxidation-state transition-metal alkylidenes play an important role in industrial processes such as alkene and alkine polymerization and other metathesis reactions. Unlike groups 5 and 6, isolable alkylidene complexes of the group 4 metals remain very elusive. This fact likely arises from the lack of suitable synthetic entries to the reactive alkylidene functionality. Only a handful of group 4 complexes having a terminal alkylidene are known. Recently we found that a hydrogen elimination reaction of 1-aza-1,3-diene titanium complexes shown below leads to a new type of stable alkylidene complexes in which the alkylidene moiety Ti=C is embedded into a metallacyclic structure. Currently we are trying to apply this unique reaction to other metals and complex types.

Stabilization of Early Transition Metals in low Oxidation States

The majority of the organometallic chemistry of titanium and zirconium involves complexes in which the metals are in their highest oxidation state +4. However, for several important chemical reactions complexes with titanium and zirconium in the +3 and +2 oxidation state have been proven as the reactive species. It is well known that 1,4-diaza-1,3-dienes are suitable ligands to stabilize metals in lower oxidation states. Currently we focus our interest to new Ti(+3) and Ti(+2) complexes with these ligands which are well-defined and easily accessible and therefore useful for studying their organometallic chemistry.Ti-Komplex

Cycloaddition Reaction of N-Heterodiene Complexes with Carbonyl Compounds

1,3-Diene complexes of early transition metals and their regio- and stereoselective carbometalations with substrates containing C=C, C=O, or C=N multiple bonds have been investigated by several groups. Less attention was given to complexes bearing N-heterodiene ligands. In our previous studies we could show that the coordination of dianionic 1,4-diaza-1,3-dienes to an electrophilic Sm(3+) ion as well as to Zr(+4) and Hf(+4) results in the specific activation of the diimine skeleton itself and affords an opportunity for a subsequent C-C coupling reaction with a dipolarophile like an organic carbonyl compound. Moreover, we have demonstrated that the reaction of carbonyl compounds with these 1,4-diaza-1,3-diene complexes can be used in the formation of new tridentate N,O,N-bound ligand systems. Now we are interested in whether this method can be used generally in ligand synthesis.

From Water Soluble Organophosphate Complexes to Polymeric Metal-Organic Framework

Metal-Organic Frameworks (MOF) are materials in which interactions between metal ions and organic ligands yield 3D structures that can be porous. We are currently investigating the reaction of metal halides with organophosphates in presence of functionalized organic molecules. Some of the crystalline polymeric products have potential in application as MOF. A crucial part of this research is the structural characterization of the newly synthesized MOF's.