Issue 48, 2018

Modifying methylalumoxane via alkyl exchange

Abstract

Methylalumoxane (MAO) ionizes highly selectively in the presence of octamethyltrisiloxane (OMTS) to generate [Me2Al·OMTS]+ [(MeAlO)16(Me3Al)6Me]. We can take advantage of this transformation to examine the reactivity of a key component of MAO using electrospray ionization mass spectrometry (ESI-MS), and here we describe the reactivity of this pair of ions with other trialkyl aluminum (R3Al) components. Using continuous injection methods, we found Et3Al to exchange much faster and extensively at room temperature in fluorobenzene (t½ ∼2 s, up to 25 exchanges of Me for Et) than iBu3Al (t½ ∼40 s, up to 11 exchanges) or Oct3Al (t½ ∼200 s, up to 7 exchanges). The exchanges are reversible and the methyl groups on the cation are also observed to exchange with the added R3Al species. These results point to the reactive components of MAO having a structure that deviates significantly from the cage-like motifs studied to date.

Graphical abstract: Modifying methylalumoxane via alkyl exchange

Supplementary files

Article information

Article type
Paper
Submitted
24 Nhl 2018
Accepted
20 Huk 2018
First published
21 Huk 2018

Dalton Trans., 2018,47, 17291-17298

Modifying methylalumoxane via alkyl exchange

H. S. Zijlstra, A. Joshi, M. Linnolahti, S. Collins and J. S. McIndoe, Dalton Trans., 2018, 47, 17291 DOI: 10.1039/C8DT04242J

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