assoz. Prof. Dr. Stephan Hohloch
Sustainable Chemistry across the Periodic Table
The Hohloch Group focuses on the use of early transition and f-Block metals in sustainable and environmentally benign applications. These span from the use of these elements in molecular magnetism, sustainable catalysis or the activation of otherwise inert small molecules such as N2, CO2, H2. Another focus of the group is to explore the general reactivity of heavy cyanates of the general formula [ChCPn]- (Ch = Chalcogen, O, S, Se and Pn = Pnictogen, N, P, As). The overall aim of the research is to find new methodologies and routes to use these basic buildings block for the synthesis of value-added chemicals and basic feedstock materials for chemical industries and specialized chemicals with potential medicine applications.
Early Transition Metal Chemistry based on chelating OCO pincer NHC and MIC ligands.
The project aims at the implementation of early transition metals into chemical processes and catalysis. Focal research points are the reduction of catalyst loading in catalysis and the discovery of new modes of reactivity using environmentally benign metals, especially of group VI metals such as molybdenum and tungsten as well as group V metals e.g., vanadium, niobium and tantalum. To reach these goals goal we develop new N-heterocyclic and mesoionic carbene ligands with intriguing electronic and steric properties holding anionic tethers/anchors to ensure flexible, yet stable coordination of the carbene towards the early transition metal center.
Typical bidentate, monoanionic PN ligand and its lanthanum complex studies in our group.
Although the chemistry of lanthanides has been explored for decades, the majority of these studies still focusses on the use of the ubiquitous cyclopentadiene ligand (C5R5) which was among the first ligands used in lanthanide chemistry. However, to develop a rich field in chemistry, also other spectator and non-spectator ligands need to be explored.
One class of ligands that has been well studied in transition metal chemistry but has only been poorly investigated in f-element chemistry, are phosphine derived ligands with chelating PN(P) coordination motifs. Our goal is to develop new, robust metal complexes using these kinds of unique ligands and study their reactivity, their electrochemical and spectroscopic properties. Recent highlights were the discovery of a light induced formation of P-P bonds or the synthesis of a bridging lanthanum phosphinidene complex.
Overview of heavy cyanate anions studied in our group.
While the chemistry of cyanates is established for almost two centuries now, the use of heavy cyanates beyond the phosphaethynolate anion ([OCP]-) is virtually unexplored. Filling this gap, we focus on the coordination chemistry of heavy cyanates with the general formular [PnCCh]- (Pn = Pnictogen atom (P and As) and Ch = Chalcogen atom (O, S and Se)) towards a large variety of elements of the the periodic table, ranging from p-block, over d-block to f-block elements. The aim is to systematically explore their chemistry across these elements, finding new modes of reactivity, e.g. cycloaddition and bond isomerization reaction. Recent highlights include the isolation of a heavy fulminate anion [SPC]- and the selective [3+2] cycloaddition reaction forming new, and otherwise inaccessible new heterocycles with intriguing properties for coordination chemistry and potential medicine applications.