Université de Fribourg

Self-assembly of Ag(I) helicates with new enantiopure 5,6-Chiragen type ligands

Mamula, Olimpia ; Bark, Thomas ; Quinodoz, Boris ; Stoeckli-Evans, Helen ; Zelewsky, Alexvon

In: Inorganica Chimica Acta, 2018, vol. 475, p. 200–206

Two new chiral bis-bidentate, C2-symmetrical ligands belonging to the Chiragen family have been synthesised and characterised. They are designed for polynuclear self-assemblies since the two (−)-5,6-pinenebipyridines units are connected by bridges whose length and rigidity avoids the coordination of the bipyridine moieties to the same metal centre. The ligand L1 with a 1,4-dimethylene...

Université de Fribourg

Synthesis and Stereochemical Properties of Chiral Square Complexes of Iron(II)

Bark, Thomas ; Zelewsky, Alexander von ; Rappoport, Dmitrij ; Neuburger, Markus ; Schaffner, Silvia ; Lacour, Jérôme ; Jodry, Jonathan

In: Chemistry - A European Journal, 2004, vol. 10(19), p. 4839-4845

The hexadentate, and ditopic ligand 2,5-bis([2,2']bipyridin-6-yl)pyrazine yields a chiral, tetrameric, square-shaped, self-assembled species upon complexation with Fe²⁺ ions. The racemate of this complex was resolved with antimonyl tatrate as the chiral auxiliary. The purity of the enantiomer was determined by NMR spectroscopy, by using a chiral, diamagnetic shift reagent, and by circular...

Université de Fribourg

Helical zinc complexes of pyrazine–pyridine hybrids

Dias, S. I. G. ; Heirtzler, Fenton ; Bark, Thomas ; Labat, Gael ; Neels, Antonia

In: Polyhedron, 2004, vol. 23 (6), p. 1011-1017

The zinc(II) complexes 1aZnCl₂ and 1bZnCl₂ (1a: 2-(6',2''-bipyrid-2'-yl)-3-(2-pyridyl)pyrazine; 1b: 2-(6',2'-bipyrid-2'-yl)-5,6-dinitrilo-3-(2-pyridyl)pyrazine) were prepared by treatment of the ligands with ZnCl₂. The structures of both were investigated by X-ray crystallography and 1H NMR spectroscopy. Both complexes display proton deshielding phenomena that are attributed to a twisted...