Die Sammlung Simone Collinet. Simone Breton als leidenschaftliche Sammlerin des Surrealismus

A series of highly active yttrium phosphasalen initiators for the heteroselective ring-opening polymerization of <i>rac</i>-lactide are reported. The initiators are yttrium alkoxide complexes ligated by iminophosphorane analogues of the popular “salen” ligand, termed “phosphasalens”. A series of novel phosphasalens have been synthesized, with varying substituents on the phenoxide rings and ethylene, propylene, <i>rac</i>-cyclohexylene, <i>R</i>,<i>R</i>-cyclohexylene, phenylene, and 2,2-dimethylpropylene groups linking the iminophosphorane moieties. Changing the substituents on the phosphasalen ligands results in changes to the rates of polymerization (<i>k</i>_obs) and to the PLA heterotacticity (<i>P</i>_s = 0.87). Generally, the initiators have high rates, excellent polymerization control, and a tolerance to low loadings

Iminophosphorane-based [P₂N₂] rhodium complexes: synthesis, reactivity, and application in catalysed transfer hydrogenation of polar bonds

International audience[Rh(P2N2)X] complexes (2-X, X = Cl, BF4) featuring a tetradentate iminophosphorane phosphine ligand were synthesised and characterised. X-Ray analysis provides evidence for a square planar geometry without coordination of the chloride anion. These complexes proved to be air-sensitive, and their oxidation to Rh(III) complexes 3-X was observed in air. The controlled reaction of 2-BF4 with one equivalent of hexachloroethane yielded [Rh(P2N2)Cl2(BF4)] (3-BF4). Direct synthesis of 3-Cl can also be achieved by coordination of the [P2N2] ligand to [RhCl(THT)3] (THT = tetrahydrothiophene). The reactivity of Rh(I) complexes 2 was further investigated, and no reaction was observed with silanes, aryl halides, or pinacolborane, although decomposition was observed under 1 atm of H2 upon prolonged heating. Interestingly, reduction of complex 3-Cl was observed by NMR upon treatment with silanes or sodium isopropoxide. Therefore, complex 3-Cl was used for catalytic transfer hydrogenation of polar bonds. The reduction of aromatic and aliphatic ketones can be carried out using 1% catalyst and 10% sodium isopropoxide, while imines are partially reduced under these conditions

Coordination chemistry with iminophosphorane ligands

International audiencePincer ligands play a preponderant role in coordination chemistry and have found applications in numerous areas ranging from organometallic reactions, catalysis, macro/supramolecular chemistry and material science.[1] They are indeed able to coordinate a large variety of metals in different oxidation state providing a strong stabilization thanks to the meridional coordination of the three adjacent coordination sites. Their popularity stems also from their synthetic tunability allowing variations of the coordinating atoms, the linker between them as well as the peripheral groups in order to adapt the ligand structure to the targeted applications.Despite the myriad of existing structures in the literature only few of them incorporate the electron-rich iminophosphorane function (P=N), which can be viewed as nitrogen ylides and behave as strong sigma and pi donors.[2] We were therefore interested in developing new iminophosphorane pincer ligand, study their coordination ability as well as the reactivity of the formed complexes.This presentation will focus on two ligand families and the reactivity of their ruthenium, iron and nickel complexes.[3]References[1] Organometallic Pincer Chemistry, in Topics in Organometallic, Eds: G. van Koten and D. Milstein chemistry, Springer-Verlag Berlin Heidelberg, 2013. [2] I. M. Marín, A. Audrey, Eur. J. Inorg. Chem. 2018, 1634-1644.[3] T. Cheisson, L. Mazaud, A. Auffrant, Dalton Trans. 2018, 47, 14521-14530

Exemples de catalyseurs à ligands iminophosphoranes

National audienceLa catalyse homogène est un des moyens privilégiés pour développer une chimie plus respectueuse de l'environnement. Dans ce contexte, les catalyseurs organométalliques jouent un rôle de premier plan et la mise au point de catalyseurs efficaces nécessite toujours un important travail de conception des ligands. Cet article montre au travers de quelques exemples comment des ligands iminophosphoranes, très électrodonneurs, ont pu être synthétisés très facilement et ont permis la mise au point de catalyseurs utilisant des métaux non toxiques (fer) ou permettant la préparation de biopolymères