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Université de Fribourg

A perfluorocyclopentene dithienylethene based molecular switch: 1,2-bis[5-(4-ethynylphenyl)-2-methylthiophen-3-yl]-3,3,4,4,5,5-hexafluorocyclopentene

Iyer, Vijay Mahadevan ; Stoeckli-Evans, Helen ; Belser, Peter

In: Acta Crystallographica E, 2006, vol. 62, no. 9, p. o3942-o3943

The title compound, C₃₁H₁₈F₆S₂, is a molecular switch based on dithienylperfluorocyclopentene. The molecule possesses pseudo-C₂ symmetry and has the open form of the switch. There are a number of intramolecular C-H...F hydrogen bonds, but in the crystal structure there are no interactions between symmetry-related molecules.

Université de Fribourg

Synthesis and structural analysis of palladium biscarbene complexes derived from bisimidazolium ligand precursors

Heckenroth, Marion ; Neels, Antonia ; Stoeckli-Evans, Helen ; Albrecht, Martin

In: Inorganica Chimica Acta, 2006, vol. 359, no. 6, p. 1929-1938

The palladation of potentially chelating bisimidazolium ligand precursors with palladium acetate gives bridging bimetallic, chelating monometallic, and homoleptic tetracarbene complexes. The coordination mode of the biscarbene ligand has been identified by spectroscopic analysis and crystallographic characterization of representative complexes, including the first example of a biscarbene A-frame...

Université de Fribourg

Catalytically active palladium pyridylidene complexes : pyridinium ionic liquids as N-heterocyclic carbene precursors

Albrecht, Martin ; Stoeckli-Evans, Helen

In: Chemical Communications, 2005, no. 37, p. 4705-4707

Pyridinium salts similar to those used as ionic liquid solvents readily undergo palladation in the presence of a base, thus giving palladium-pyridylidene N-heterocyclic carbene complexes that are active catalysts for Suzuki-type cross-coupling reactions.

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

Novel HEXOL-type cyclometallated iridium(III) complexes: stereoselective synthesis and structure elucidation

Yang, Liangru ; Zelewsky, Alexander von ; Stoeckli-Evans, Helen

In: Chemical Communications, 2005, vol. (33), p. 4155

Two diastereoisomers of tetranuclear cyclometallated iridium complexes, either having an inner core of HEXOL-type [Ir(IrCl₂)₃]⁶⁺ unit and a surface of six chiral, didentate, cyclometallated ligands, are stereoselectively synthesized from an enantiopure pinenopyridine derivative.

Université de Fribourg

Diastereoselective synthesis of coordination compounds: a chiral tripodal ligand based on bipyridine units and its ruthenium(II) and iron(II) complexes

Hamann, Christine ; Zelewsky, Alexander von ; Neels, Antonia ; Stoeckli-Evans, Helen

In: Dalton Transactions, 2004, vol. 3, p. 402-406

The enantiomerically pure chiral tris-chelating ligand (+)-(7S,10R)-L(L) comprising three 4,5-pinenobipyridine subunits connected through a mesityl spacer has been synthesized. Complexes of L with RuII and FeII have been prepared and characterised. NMR spectroscopy indicates that...