First Stabilization of 14‐Electron Rhodium(I) Complexes by Hemichelation

Hemichelation is emerging as a new mode of coordination where non‐covalent interactions crucially contribute to the cohesion of electron‐unsaturated organometallic complexes. This study discloses an unprecedented demonstration of this concept to a Group 9 metal, that is, Rh^I. The syntheses of new 14‐electron Rh^I complexes were achieved by choosing the anti‐[(η⁶:η⁶‐fluorenyl){Cr(CO)₃}₂] anion as the ambiphilic hemichelating ligand, which was treated with [{Rh(nbd)Cl}₂] (nbd=norbornadiene) and [{Rh(CO)₂Cl}₂]. The new T‐shaped Rh^I hemichelates were characterized by analytical and structural methods. Investigations using the methods of the DFT and electron‐density topology analysis (NCI region analysis, QTAIM theory) confirmed the closed‐shell, non‐covalent and attractive characters of the interaction between the Rh^I center and the proximal Cr(CO)₃ moiety. This study shows that, by appropriate tuning of the electronic properties of the ambiphilic ligand, truly coordination‐unsaturated Rh^I complexes can be synthesized in a manageable form.     

The Influence of the Framework: An Anion‐Binding Study Using Fused [n]Polynorbornanes

A series of bis‐thiourea‐functionalized [n]polynorbornane hosts ( 1 – 6 ) with increasing size were synthesized and their anion‐binding properties were evaluated by using ¹H NMR spectroscopic titration and Job’s plot analysis. The larger bis‐thiourea‐[3]polynorbornane scaffolds 4 and 5 bound acetate in a 1:1 (cooperative) arrangement, whereas the corresponding smaller norbornane host 2 , identical in preorganization, bound acetate in a 1:2 (independent) arrangement. In contrast, the size of the framework had no influence on the binding of dihydrogenphosphate. These results clearly highlight the subtle influence that the framework itself can have on host–guest interactions.     

The divergence theorem for unbounded vector fields

In the context of Lebesgue integration, we derive the divergence theorem for unbounded vector fields that can have singularities at every point of a compact set whose Minkowski content of codimension greater than two is finite. The resulting integration by parts theorem is applied to removable sets of holomorphic and harmonic functions.

     

Bestimmung, Trennung und Eigenschaften der unverseifbaren Bestandteile der Fette

Ohne Zusammenfassung     

Five-level k · p model for conduction electrons in GaAs. Description of cyclotron resonance experiments

Five-level k·p model for the conduction electrons in GaAs in the presence of a quantising magnetic field is developed and used to describe spin splittings of the cyclotron resonance and the donor-shifted cyclotron resonance peaks, observed in this material up to fields of 22.5 T. It is shown that the spin splittings are insensitive to polaron effects and that their values can be very well described by the model.Required band parameters correctly account for the rate of electron spin relaxation in GaAs due to inversion asymmetry, as determined by other authors.