Herein we report on the cross-coupling reaction of phenylmagnesium bromide with aryl halides using the well-defined tetrahedral Ni(I) complex, [(Triphos)Ni I Cl] (Triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane). In the presence of 0.5 mol % [(Triphos)Ni I Cl], good to excellent yields (75-97%) of the respective coupling products within a reaction time of only 2.5 h at room temperature were achieved. Likewise, the tripodal Ni(II)complexes [(κ 2 -Triphos)Ni II Cl 2 ] and [(κ 3 -Triphos)Ni II Cl](X) (X = ClO 4 , BF 4 ) were tested as potential pre-catalysts for the Kumada cross-coupling reaction. While the Ni(II) complexes also afford the coupling products in comparable yields, mechanistic investigations by UV/Vis and electron paramagnetic resonance (EPR) spectroscopy indicate a Ni(I) intermediate as the catalytically active species in the Kumada cross-coupling reaction. Based on experimental findings and density functional theory (DFT) calculations, a plausible Ni(I)-catalyzed reaction mechanism for the Kumada cross-coupling reaction is presented.

While [Ni(cyclam)]2+ and [Ni(dithiacyclam)]2+ complexes were shown to be potent electrocatalysts for the CO2 conversion, their respective Co complexes hitherto received only little attention. Herein, we report on the CoII complexes of the cyclam and dithiacyclam platform, describe their synthesis and reveal their rich solvent dependent coordination chemistry. We show that sulfur implementation into the cyclam moiety leads to a switch from a low spin CoII complex in [Co(cyclam)]2+ to a high spin form in [Co(dithiacyclam)]2+. Notably, while both complexes are capable to perform the reduction of CO2 to CO, H2 formation is generally preferred. Along this line, the complexes were shown to enable proton reduction from acetic acid. However, in comparison to [Co(cyclam)]2+, the altered electronics make [Co(dithiacyclam)]2+ complexes prone to deposit on the glassy carbon working electrode over time leading to an overall low faradaic efficiency for the reduction of protons or CO2.

The selective reduction of CO 2 is of high interest toward future applications as a C1-building block. Therefore, metal complexes that allow for the formation of specific CO 2 reduction products under distinct reaction conditions are necessary. A detailed understanding of the CO 2 reduction pathways on a molecular level is, however, required to help in designing catalytic platforms for efficient CO 2 conversion with specific product formation. Reported herein is a unique example of a solvent-controlled reduction of CO 2 using a Triphos-based iron hydride complex. In THF, CO 2 reduction selectively leads to CO formation, whereas experiments in acetonitrile exclusively afford formate, HCOO − . In order to explain the experimental findings, theoretical calculations of the reaction pathways were performed and further demonstrate the importance of the applied solvent for a selective reduction of CO 2 .

A cancer stem cell (CSC) active, solution stable, silver(I) polymeric complex bearing a dithiacyclam ligand is reported. The complex displays similar potency towards CSCs as salinomycin in monolayer and three-dimensional...

Herein, we report a simplified method for the synthesis of Triphos homologs HCC(CHX)(CHY) (X = SPh, Y = PPh, n = 0-3). The multidentate compounds were tested for their potential to coordinate metals such as Ni, Fe, and Mo under the same experimental conditions. Cyclic voltammetry, spectroelectrochemical IR investigations as well as DFT calculations were used to examine the electronic alterations in a series of [{HCC(CHX)(CHY)}Mo(CO)] complexes and to evaluate their potential to open coordination sites or to release CO upon oxidation or in the presence of different solvents. In addition, we demonstrate that the catalytic hydrosilylation of N,N-dimethylbenzamide to N,N-dimethylbenzylamine is influenced by the applied tripodal ligand. Our investigations show the high potential of such manipulations to selectively alter the dynamics of the binding properties of Triphos-metal complexes and their reactivity.