Mass Spectrometric Characterization of Methylaluminoxane

详细信息    查看全文

• 作者：Tyler K. Trefz ; Matthew A. Henderson ; Miles Y. Wang ; Scott Collins ; J. Scott McIndoe
• 刊名：Organometallics
• 出版年：2013
• 出版时间：June 10, 2013
• 年：2013
• 卷：32
• 期：11
• 页码：3149-3152
• 全文大小：226K
• 年卷期：v.32,no.11(June 10, 2013)
• ISSN：1520-6041

文摘

Electrospray ionization mass spectrometric studies of poly(methylaluminoxane) (MAO) in the presence of Cp₂ZrMe₂, octamethyltrisiloxane (OMTS), or [Bu₄N]Cl in fluorobenzene solution are reported. The results concur with the hypothesis that MAO is partially ionized in sufficiently polar media, where the contact ion pairs are of the general formula [Me₂Al][(MeAlO)_x(AlMe₃)_yMe]. A limited number of compositions of this type are detected; the most abundant has x = 23 and y = 7, where the cation [Me₂Al(OMTS)]⁺ (with m/z 293) and the anion (with m/z 1853) were detected in the presence of OMTS, which stabilizes the Me₂Al cation. The results demonstrate that MAO ionizes Cp₂ZrMe₂ by acting as a source of this electrophilic cation, giving rise to an ion pair featuring a large and weakly coordinating aluminoxanate counterion.