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Are Methylaluminoxane Activators Sheets?
Author(s) -
Collins Scott,
Hasan Galib,
Joshi Anuj,
McIndoe J. Scott,
Linnolahti Mikko
Publication year - 2021
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.202100268
Subject(s) - fluorobenzene , chemistry , methylaluminoxane , hydrolysis , polarizability , ionization , ion , crystallography , stereochemistry , photochemistry , organic chemistry , metallocene , molecule , polymer , polymerization , benzene
Density functional theory calculations on neutral sheet models for methylaluminoxane (MAO) indicate that these structures, containing 5‐coordinate and 4‐coordinate Al, are likely precursors to ion‐pairs seen during the hydrolysis of trimethylaluminum (Me 3 Al) in the presence of donors such as octamethyltrisiloxane (OMTS). Ionization by both methide ([Me] − ) and [Me 2 Al] + abstraction, involving this donor, were studied by polarizable continuum model calculations in fluorobenzene (PhF) and o‐difluorobenzene (DFB) media. These studies suggest that low MW, 5‐coordinate sheets ionize by [Me 2 Al] + abstraction, while [Me] − abstraction from Me 3 Al‐OMTS is the likely process for higher MW 4‐coordinate sheets. Further, comparison of anion stabilities per mole of aluminoxane repeat unit (MeAlO) n , suggest that anions such as [(MeAlO) 7 (Me 3 Al) 4 Me] − =[ 7,4 ] − are especially stable compared to higher homologues, even though their neutral precursors are unstable.