Porphyrins Fused to N‐Heterocyclic Carbenes (NHCs): Modulation of the Electronic and Catalytic Properties of NHCs by the Central Metal of the Porphyrin |
| |
Authors: | Dr. Jean‐François Lefebvre Dr. Mamadou Lo Dr. Jean‐Paul Gisselbrecht Dr. Olivier Coulembier Dr. Sébastien Clément Dr. Sébastien Richeter |
| |
Affiliation: | 1. Institut Charles Gerhardt de Montpellier, UMR 5253, Université Montpellier 2, CC 1701, Place E. Bataillon, 34095 Montpellier Cedex 05 (France), Fax: (+33)?4‐6714‐3852;2. Laboratoire d'Electrochimie et de Chimie Physique du Corps Solide, Institut de Chimie, UMR 7177 CNRS Université de Strasbourg, 4 rue Blaise Pascal, 67000 Strasbourg (France);3. Laboratory of Polymeric and Composite Materials (LPCM), Center of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons (UMONS), Place du Parc 20, 7000 Mons (Belgium) |
| |
Abstract: | We report herein a detailed study of the use of porphyrins fused to imidazolium salts as precursors of N‐heterocyclic carbene ligands 1 M . Rhodium(I) complexes 6 M – 9 M were prepared by using 1 M ligands with different metal cations in the inner core of the porphyrin (M=NiII, ZnII, MnIII, AlIII, 2H). The electronic properties of the corresponding N‐heterocyclic carbene ligands were investigated by monitoring the spectroscopic changes occurring in the cod and CO ancillary ligands of [( 1 M )Rh(cod)Cl] and [( 1 M )Rh(CO)2Cl] complexes (cod=1,5‐cyclooctadiene). Porphyrin–NHC ligands 1 M with a trivalent metal cation such as MnIII and AlIII are overall poorer electron donors than porphyrin–NHC ligands with no metal cation or incorporating a divalent metal cation such as NiII and ZnII. Imidazolium salts 3 M (M=Ni, Zn, Mn, 2H) have also been used as NHC precursors to catalyze the ring‐opening polymerization of L ‐lactide. The results clearly show that the inner metal of the porphyrin has an important effect on the reactivity of the outer carbene. |
| |
Keywords: | carbenes organocatalysis porphyrinoids ring‐opening polymerization UV/Vis spectroscopy |
|
|