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Université de Fribourg

1,2,3-triazolylidenes as versatile abnormal carbene ligands for late transition metals

Mathew, Paulson ; Neels, Antonia ; Albrecht, Martin

In: Journal of the American Chemical Society, 2008, vol. 130, no. 41, p. 13534–13535

The [3 + 2] cycloaddition of azides and acetylenes followed by nitrogen quaternization was applied for the generation of novel and highly modular triazolium salts. The selective substitution of the 1,3,4-substitution pattern presets such salts as precursors for a new class of abnormal carbene ligands, thus expanding the family of these high-impact ligands. Metalation of the triazolium salts is...

Université de Fribourg

Catalytic hydrogenation using abnormal N-heterocyclic carbene palladium complexes: catalytic scope and mechanistic insights

Heckenroth, Marion ; Khlebnikov, Vsevolod ; Neels, Antonia ; Schurtenberger, Peter ; Albrecht, Martin

In: ChemCatChem, 2011, vol. 3, no. 1, p. 167-173

Palladium complexes containing abnormally bound C4-bound dicarbene ligands have been exploited for catalytic alkene hydrogenation. Comparison to normally C2-bound homologues indicates that the carbene bonding mode critically influences the catalytic activity. Good catalytic performance in the hydrogenation of cis-disubstituted olefins and non-isomerizable terminal olefins under mild...

Université de Fribourg

Chelating C4-bound imidazolylidene complexes through oxidative addition of imidazolium salts to palladium(0)

Krüger, Anneke ; Kluser, Evelyne ; Müller-Bunz, Helge ; Neels, Antonia ; Albrecht, Martin

In: European Journal of Inorganic Chemistry, 2012, p. -

Oxidative addition of donor-functionalised 4-iodoimidazolium salts to palladium(0) provides a selective route for the preparation of abnormal chelating N-heterocyclic carbene complexes and enables the introduction of a variety of donor groups. The activation of the C4 position does not necessitate protection of the imidazolium C2 position, thereby leaving this site available for further...

Université de Fribourg

Chelating NHC ruthenium(II) complexes as robust homogeneous hydrogenation catalysts

Gandolfi, Claudio ; Heckenroth, Marion ; Neels, Antonia ; Laurenczy, Gbor ; Albrecht, Martin

In: Organometallics, 2009, vol. 28, no. 17, p. 5112–5121

A series of ruthenium(II) complexes have been prepared by using bidentate chelating N-heterocyclic carbene (NHC) ligands that feature different donor groups E (E = olefin, thioether, carboxylate, and NHC). Rigid coordination of all donor sites was concluded from NMR spectroscopy, and the electronic impact of the donor group was evaluated by electrochemical analyses. The chelating donor group had...

Université de Fribourg

Crystal structures of trans-di­chlorido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1H-imidazole-ΚN³]iron(II), trans-di­bromido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1H-imidazole-ΚN³]iron(II) and trans-di­bromido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1H-imidazole-ΚN³]iron(II) diethyl ether disolvate

Mafua, Roger ; Jenny, Titus ; Labat, Gael ; Neels, Antonia ; Stoeckli-Evans, Helen

In: Acta Crystallographica Section E Structure Reports Online, 2014, vol. 70, no. 8, p. 72–76

The title compounds, [FeCl₂(C₁₅H₂₀N₂)₄], (I), [FeBr₂(C₁₅H₂₀N₂)₄], (II), and [FeBr₂(C₁₅H₂₀N₂)₄]·2C₄H₁₀O, (IIb), respectively, all have triclinic symmetry, with (I) and (II) being isotypic. The FeII atoms in each of the structures are located on an inversion center. They have octa­hedral FeX₂N₄ (X = Cl and Br,...

Université de Fribourg

Diastereoselective preparation of Cu(I) and Ag(I) double helices by the use of chiral bis-bipyridine ligands

Perret-Aebi, Laure-Emmanuelle ; Zelewsky, Alexander von ; Neels, Antonia

In: New Journal of Chemistry, 2009, vol. 33, p. 462–465

Chiral bis-5,6-pinene bipyridine type ligands have been used to form, through self-assembly reaction, dinuclear coordination compounds which show a highly diastereoselective formation of double helices with copper(I) and silver(I) as coordination centers.

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...

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...

Université de Fribourg

Main-chain organometallic polymers comprising redox-active iron(II) centers connected by ditopic N-heterocyclic carbenes

Mercs, Laszlo ; Neels, Antonia ; Stoeckli-Evans, Helen ; Albrecht, Martin

In: Dalton Transactions, 2009, vol. 35, p. 7168-7178

Main-chain organometallic polymers were synthesized from bimetallic iron(II) complexes containing a ditopic N-heterocyclic carbene (NHC) ligand [(cp)(CO)LFe(NHC∼NHC)Fe(cp)(CO)L]X₂ (where NHC∼NHC represents a bridging dicarbene ligand, L = I⁻ or CO). Addition of a diimine ligand such as pyrazine or 4,4′-bipyridine, interconnected these bimetallic complexes and gave the...