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Formation and Structure of Hydrolytic Methylaluminoxane Activators.

ABSTRACT: Methylaluminoxane (MAO) activators have sheet structures which form ion-pairs on reaction of neutral donors such as octamethyltrisiloxane (OMTS). The ion-pairs can be detected by electrospray ionization mass spectrometry (ESI-MS) in polar media. The growth of these reactive precursors during hydrolysis of Me₃ Al can be monitored using ESI-MS. Density functional theory, combined with numerical simulation of growth, indicates that this process involves rapid formation of low MW oligomers, followed by assembly of these species into low MW sheets. These can grow through further addition of low MW oligomers or by fusion into larger sheets. The mechanism of these growth processes leads to the prediction that even-numbered sheets should be favored, and this surprising result is confirmed by ESI-MS monitoring experiments of both activator growth and MAO aging.

SUBMITTER: Collins S

PROVIDER: S-EPMC8596698 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature

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Formation and Structure of Hydrolytic Methylaluminoxane Activators.

Collins Scott S Joshi Anuj A Linnolahti Mikko M

Chemistry (Weinheim an der Bergstrasse, Germany) 20211006 62

Methylaluminoxane (MAO) activators have sheet structures which form ion-pairs on reaction of neutral donors such as octamethyltrisiloxane (OMTS). The ion-pairs can be detected by electrospray ionization mass spectrometry (ESI-MS) in polar media. The growth of these reactive precursors during hydrolysis of Me<sub>3</sub> Al can be monitored using ESI-MS. Density functional theory, combined with numerical simulation of growth, indicates that this process involves rapid formation of low MW oligomer ...[more]

PMID: 34436806

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