Evidence for Methylaluminoxane (MAO) Molecular Structure and Reactivity from Ultrahigh Magnetic Field <sup>27</sup> Al MAS NMR Spectroscopy Combined with DFT Calculations
Abstract
Abstract The structure and reactivity of methylaluminoxane (MAO), a reagent of major interest for olefin polymerization, both industrially and academically, has been probed using ultrahigh magnetic field solid‐state NMR (28.2 T, 1200 MHz for 1 H Larmor frequency). High resolution methods combined with density functional calculations allowed for the identification and quantification of five major aluminum sites, providing precise information on the structure of MAO at the molecular level. Based on reactivity studies with THF and [ZrCp 2 Me 2 ], the main reactive centers are identified as bismethyl aluminum species stabilized via a bridging methyl group from a neighboring Al center, featuring both high chemical shift and quadrupolar coupling constants (162 ppm and 27.4 MHz, respectively). This approach demonstrates the ability to monitor the chemistry of MAO with unprecedented precision, enabling a state‐of‐the‐art understanding of its structure and reactivity.
Article Details
Authors (9)
Kai Szeto
Laboratoire de Catalyse Polymérisation Procédés et Matériaux (CP2M) CNRS UMR 5128 Univ. Lyon 1, CPE Lyon Université de Lyon Villeurbanne F‐69616 France
Mostafa Taoufik
Laboratoire de Catalyse Polymérisation Procédés et Matériaux (CP2M) CNRS UMR 5128 Univ. Lyon 1, CPE Lyon Université de Lyon Villeurbanne F‐69616 France
Franck Fayon
CEMHTI, CNRS, University of Orléans, 1D Avenue de la Recherche Scientifique, 45071 Orléans Cedex 2, France
David Gajan
ENS Lyon, CNRS, Univ Claude Bernard Lyon 1, CRMN (Centre de RMN Très Hauts Champs de Lyon UMR 5082), 5 rue de la Doua, 69100 Villeurbanne, France
Eva Zurek
Department of Chemistry, State University of New York at Buffalo, 777 Natural Science Complex, Buffalo, New York 14260-3000, United States
Jochen Autschbach
Department of Chemistry
Julien Trébosc
FR 2638 – IMEC – Fédération Chevreul Univ. Lille, CNRS, INRAE Centrale Lille Univ. Artois Lille F‐59000 France
Laurent Delevoye
Unité de Catalyse et Chimie du Solide (UCCS) UMR 8181 Univ. Lille CNRS Centrale Lille Univ. Artois Lille 59000 France
Régis M. Gauvin
Institut de Recherche de Chimie Paris Chimie ParisTech PSL University CNRS 11 rue Pierre et Marie Curie Paris 75005 France