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Université de Fribourg

Stereoselectivity in the formation of tris-diimine complexes of Fe(II), Ru(II), and Os(II) with a C₂-symmetric chiral derivative of 2,2′-bipyridine

Drahoňovský, Dušan ; Knof, Ulrich ; Jungo, Laurence ; Belser, Thomas ; Neels, Antonia ; Labat, Gaël Charles ; Stoeckli-Evans, Helen ; Zelewsky, Alexander von

In: Dalton Transactions, 2006, p. 1444 - 1454

A C₂-symmetric enantiopure 4,5-bis(pinene)-2,2′-bipyridine ligand (–)-L was used to investigate the diastereoselectivity in the formation of [ML₃]²⁺ coordination species (M = Fe(II), Ru(II), Os(II), Zn(II), Cd(II), Cu(II), Ni(II)), and [ML₂Cl₂] (M = Ru(II), Os(II)). The X-ray structures of the [ML₃]²⁺ complexes were determined for Δ-[FeL₃](PF₆)₂,...

Université de Fribourg

Synthesis and application of an electronically chiral mimic of CpFe

Allemann, Christophe ; Jenny, Titus (Dir.)

Thèse de doctorat : Université de Fribourg, 2002 ; No 1369.

The field of new optically active and reactive organometallic species is of tremendous interest. Within this area, (-)-(1S)-dicarbonyliodide[μ5-(2,8,8-tri-methylbicyclo[3.2.1]oct-3,6-diene)2-yl] iron (1), called 2-Me-BOD-Fe(CO)2I, emerges as a new stage in the development of chiral cyclopentadienyl-like complexes. Studying the reactivity of 1 has shown that both its non-contiguous μ5-system and...

Université de Fribourg

A study of the photophysical and photochemical properties of metal complexes using density functional theory

Buchs, Matthieu ; Daul, Claude (Dir.) ; Schläpfer, Carl-Wilhelm (Codir.) ; Weber, Jacques (Codir.)

Thèse de doctorat : Université de Fribourg, 2001 ; no 1332.

The first objective of this thesis is the calculation of excited state energies and properties of transition metal complexes using Density Functional Theory (DFT). To explore this wide topic, we did choose three different chemical systems. The first one, presented in the chapter 4, is about the photodissociation of the tris(2,2’- bipyridine)ruthenium(II) ([Ru(bpy)3]2+) ion. Over the last two...

Université de Fribourg

Protonation behaviour of chiral tetradentate polypyridines derived from α-Pinene

Düggeli, Mathias ; Christen, Tobias ; Zelewsky, Alexander von

In: Chemistry - A European Journal, 2005, vol. 11, p. 185-194

Detailed protonation experiments of the [5,6]-pinenebipyridine molecule and the unsubstituted [4,5]- and [5,6]-CHIRAGEN[0] ligands in various solvents indicate a variety of structures of the protonated species. UV-visible and NMR measurements (including ¹⁵N chemical shifts) show the transition from trans to cis conformation of [5,6]-pinenebipyridine upon protonation. The...

Université de Fribourg

Asymmetric Synthesis of Coordination Compounds: Back to the Roots. Diastereoselective Synthesis of Simple Platinum(IV) Complexes

Drahoňovský, Dušan ; Zelewsky, Alexander von

In: Helvetica Chimica Acta, 2005, vol. 88(3), p. 496-506

A publication by Alexander P. Smirnoff in Helvetica Chimica Acta in 1920 [6] describes the first synthesis of a coordination species, i.e., of tris(propane-1,2-diamine-κN¹,κN²)platinum(4+) ([PtIV(pn)₃]⁴⁺), where it was shown that the configuration of a chiral center in the ligand can influence the configuration at the metal. The present investigation of...

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

Der hexadentate und ditopische Ligand 2,5-Bis([2,2']bipyridin-6-yl)pyrazin bildet bei der Selbstorganisationsreaktion mit Fe²⁺-Ionen einen chiralen, quadratförmigen Tetramerkomplex. Das Racemat dieses Komplexes wurde mit Hilfe von Antimonyltartrat in die Enantiomere getrennt. Die Reinheit des Enantiomers wurde durch NMR-Spektroskopie unter Zuhilfenahme eines chiralen, diamagnetischen...

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, no. 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...