Alkoxylation of the imine carbon atom of a Schiff-base ligand upon coordination to arene ruthenium

Publication date: Available online 17 July 2018Source: Inorganica Chimica ActaAuthor(s): Wassila Aboura, Tayeb Benabdallah, Fan Zhang, Bruno TherrienAbstractThe Schiff-base 5-methyl-4-{(pyridin-2-ylmethylene)amino}-4H-1,2,4-triazole-3-thiol (L-H) reacts in alcoholic solution (methanol, ethanol, isopropanol) at room temperature with the dinuclear precursor [(η6-MeC6H4Pri)RuCl2]2 to give a series of neutral complexes of the general formula (η6-MeC6H4Pri)Ru(L-OR) (R = Me, 1; R = Et, 2; R = Pri, 3). In these complexes, the Schiff-base ligand coordinates to the arene ruthenium unit in a S,N,N-tridentate fashion and concomitantly to the coordination process a nucleophilic addition of the alcohol occurs on the imine carbon of L, thus forming the corresponding L-OR ligand. The molecular structure of 3, solved by single-crystal X-ray analysis, shows a piano-stool arrangement with the p-cymene, the Sthiolato, the Nimine and Npyridyl surrounding the chiral-at-metal ruthenium center and an OPri group attached to the imine carbon. The insertion of an alkoxy group on the carbon atom reduces the imine function and introduces chirality on the ligand, thus generating a second chiral center and potentially diastereoisomeric complexes. However, steric hindrance on the ligand forces the formation of only one pair of enantiomers.Graphical abstractAlkoxylation of a Schiff-base ligand has occurred during the formation of arene ruthenium complexes, thus generating a stable chiral hemiaminal deriva...

Source: Inorganica Chimica Acta - July 18, 2018 Category: Chemistry Source Type: research