Today, almost all industrial chemicals have involved a catalytic reaction step during their manufacturing process with palladium and platin compounds being used as the most common catalysts. However, nickel also forms a wide variety of organometallic compounds and the big advantage of using them as catalysts is the much lower cost. Therefore, the aim of this work was to gain a better understanding of the reactivity of Ni(0) complexes and thus finding novel ways to replace expensive noble metal catalysts. Bicyclopropylidene (bcp), dicyclopropylacetylene (dcpa) and 1,4-dimethoxy-2- butyne (dmbu), which have been synthesized previously in the research group of Prof. A. de Meijere (University of Göttingen), are interesting molecular building blocks in various transition metal-catalyzed cyclization reactions and were used as ligands in substitution reactions with the Ni(0) complex [Ni(bipy)(COD)]. These reactions were investigated kinetically and structures of the product complexes as well as isoelectronic copper(I) complexes could be obtained.In collaboration with the research group of Prof. P. R. Schreiner (JLU Gießen) efforts were made to obtain copper(I) and nickel(0) coordination polymers with the adamantane derivative tetracyclo[7.3.1.1(4,12).0(2,7)]tetradeca-6.11-diene (tctd). It was possible to obtain the molecular structure of the copper(I) polymer [Cu2Cl2)(CH3CN)(tctd)]n for the first time.Furthermore, studies on ligand exchange reactions of the nickel(0) complex bis(cyclooctadiene)nickel(0) ([Ni(COD)2]) and N-Donor ligands have been performed. Efforts synthesizing a binuclear nickel(0) complex using the tetradentate ligand 1,2-bis(2,2´-bipyridine-6-yl)ethane (O-BPy) afforded the complex [Ni2(O-BPy)(eta2 C4H6)2]. Since no butadiene was used as an educt in this reaction a cleavage of COD catalyzed by the nickel(0) complex was supposed. Within a collaboration with the research group of Prof. M. C. Holthausen (Goethe University Frankfurt am Main) DFT calculations on this reaction were performed. Efforts were made to investigate this reaction in more detail using the ligand O-BPy and derivatives. It was possible to structurally characterize several mononuclear complexes with the applied ligands. Furthermore, isoelectronic copper(I) complexes with O-BPy were also prepared. It was possible to synthesize and structurally characterize the copper(I) complex [Cu2(O-BPy)(COD)2] .Developing transition metal complexes, which are able to selectively and catalytically oxidize organic substrates, is a challenging task in today s chemistry. Therefore, studies on the activation of small molecules (e.g. O2, NO, N2O) and the formation of short-lived model metal-oxygen intermediates are of great interest. The number of reported nickel-oxygen intermediates has been comparatively low in this field. Efforts were made in this work to synthesize nickel-dioxygen adducts with the macrocyclic ligands 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (14-tmc) and rac-5,5,7,12,12,14-hexymethyl-1,4,8,11-tetraazacyclotetradecane (tetB). By reducing [Ni(14-tmc)](ClO4)2 with NaHg to the nickel(I) complex and reacting it with gaseous N2O, it was the aim to obtain a nickel-oxo complex. This species was most likely formed as an intermediate. However, it was only possible to isolate and characterize the nickel-hydroxo complex Na[Ni2(14-tmc)2(OH)2](ClO4)3. By using the complex [Ni(14-tmc)]SO3CF3 it was possible to obtain a stable nickel nitrous oxide adduct complex which might provide access to a nickel-oxo species.
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