The Classic “Brown-Ring” Reaction in a New Medium: Kinetics, Mechanism, and Spectroscopy of the Reversible Binding of Nitric Oxide to Iron(II) in an Ionic Liquid

Inorganic reaction mechanisms. A personal journey

This review covers highlights of the work performed in the van Eldik group on inorganic reaction mechanisms over the past two decades in the form of a personal journey. Topics that are covered include, from NO to HNO chemistry, peroxide activation in model porphyrin and enzymatic systems, the wonder-world of Ru^III(edta) chemistry, redox chemistry of Ru(iii) complexes, Ru(ii) polypyridyl complexes and their application, relevant physicochemical properties and reaction mechanisms in ionic liquids, and mechanistic insight from computational chemistry. In each of these sections, typical examples of mechanistic studies are presented in reference to related work reported in the literature.

Ionic liquid promotes N2 coordination to titanocene(iii) monochloride

Coordination of N₂ to [(Cp₂TiCl)₂] in a non-coordinating ionic liquid, Pyr₄FAP, was studied by UV-vis/NIR and EPR spectroscopies. [(Cp₂TiCl)₂] is in equilibrium between monomeric [Cp₂TiCl] and dimeric species [(Cp₂TiCl)₂]. The frozen solution EPR spectrum revealed the coordination of N₂ to [Cp₂TiCl], suggesting that Pyr₄FAP promotes N₂ coordination to the Ti(iii) center.

High-pressure salt templating strategy toward intact isochoric hierarchically porous carbon monoliths from ionic liquids

Using a high-pressure salt templating approach, a crack-free, hierarchically porous carbon monolith with good monolithic formability and integrity was prepared from an ionic liquid.

Elucidation of inorganic reaction mechanisms in ionic liquids: the important role of solvent donor and acceptor properties

In this article, we focus on the important role of solvent donor and acceptor properties of ionic liquids in the elucidation of inorganic reaction mechanisms. For this purpose, mechanistic and structural studies on typical inorganic reactions, performed in ionic liquids, have been conducted. The presented systems range from simple complex-formation and ligand-substitution reactions to the activation of small molecules by catalytically active complexes. The data obtained for the reactions in ionic liquids are compared with those for the same reactions carried out in conventional solvents, and are discussed with respect to the donor and acceptor properties of the applied ionic liquids. The intention of this perspective is to gain more insight into the role of ILs as solvents and their interaction with metal ions and complexes in solution.

Coordination of terpyridine to Li+ in two different ionic liquids

On the basis of (7)Li NMR experiments, the complex-formation reaction between Li(+) and the tridentate N-donor ligand terpyridine was studied in the ionic liquids [emim][NTf2] and [emim][ClO4] as solvents. For both ionic liquids, the NMR data implicate the formation of [Li(terpy)2](+). Density functional theory calculations show that partial coordination of terpyridine involving the coordination of a solvent anion can be excluded. In contrast to the studies in solution, X-ray diffraction measurements led to completely different results. In the case of [emim][NTf2], the polymeric lithium species [Li(terpy)(NTf2)]n was found to control the stacking of this complex, whereas crystals grown from [emim][ClO4] exhibit the discrete dimeric species [Li(terpy)(ClO4)]2. However, both structures indicate that each lithium ion is formally coordinated by one terpy molecule and one solvent anion in the solid state, suggesting that charge neutralization and π stacking mainly control the crystallization process.