728042-52-2Relevant academic research and scientific papers
Stable anilinyl radicals coordinated to nickel: X-ray crystal structure and characterization
Kochem, Amelie,Gellon, Gisele,Leconte, Nicolas,Baptiste, Benoit,Philouze, Christian,Jarjayes, Olivier,Orio, Maylis,Thomas, Fabrice
, p. 16707 - 16721 (2013)
Two anilinosalen and a mixed phenol-anilinosalen ligands involving sterically hindered anilines moieties were synthesized. Their nickel(II) complexes 1, 2, and 3 were prepared and characterized. They could be readily one-electron oxidized (E1/2=-0.30, -0.26 and 0.10 V vs. Fc +/Fc, respectively) into anilinyl radicals species [1]+, [2]+, and [3]+, respectively. The radical complexes are extremely stable and were isolated as single crystals. X-ray crystallographic structures reveal that the changes in bond length resulting from oxidation do not exceed 0.02 A within the ligand framework in the symmetrical [1] + and [2]+. No quinoid bond pattern was present. In contrast, larger structural rearrangements were evidenced for the unsymmetrical [3]+, with shortening of one Cortho-Cmeta bond. Radical species [1]+ and [2]+ exhibit a strong absorption band at around 6000 cm-1 (class III mixed valence compounds). This band is significantly less intense than [3]+, consistent with a rather localized anilinyl radical character, and thus a classification of this species as class II mixed-valence compound. Magnetic and electronic properties, as well as structural parameters, have been computed by DFT methods.
New ruthenium catalysts containing chiral Schiff bases for the asymmetric hydrogenation of acetophenone
Karame, Iyad,Jahjah, Mohamed,Messaoudi, Abdelhalim,Tommasino, M. Lorraine,Lemaire, Marc
, p. 1569 - 1581 (2007/10/03)
A series of new chiral N4-Schiff bases, containing amine or sulfonamide functionalities has been synthesized. Coupled with ruthenium catalysts, these Schiff bases induce interesting results in the hydrogenation of acetophenone: complete conversion and 76% ee were obtained with the catalytic system Ru(PPh3)3Cl2/(1R,2R)-N,N′-bis-(2- p-tosylaminobenzylidene)-1,2-diphenylethylenediamine. A very important phosphine co-ligand effect was observed on both activity and enantioselectivity of the catalysts. However, without the co-ligand, we obtained an enantioselectivity for the (R)-enantiomer, whereas with nonchiral co-ligand an enantioselectivity for the (S)-enantiomer was observed.
