Mass spectrometric characterization of methylaluminoxane-activated metallocene complexes
| dc.contributor.author | Trefs, Tyler K. | |
| dc.contributor.author | Henderson, Matthew A. | |
| dc.contributor.author | Linnolahti, Mikko | |
| dc.contributor.author | Collins, Scott | |
| dc.contributor.author | McIndoe, J. Scott | |
| dc.date.accessioned | 2017-04-24T16:31:17Z | |
| dc.date.available | 2017-04-24T16:31:17Z | |
| dc.date.copyright | 2014 | en_US |
| dc.date.issued | 2014 | |
| dc.description.abstract | Electrospray ionization mass spectrometric studies of poly(methylaluminoxane) (MAO) in the presence of Cp2ZrMe2, Cp2ZrMe(Cl) and Cp2ZrCl2 in fluorobenzene (PhF) solution are reported. The results demonstrate that alkylation and ionization are separate events that occur at competitive rates in a polar solvent. Further, there are significant differences in ion pair speciation that result from the use of metallocene dichloride complexes vs. alkylated precursors at otherwise identical Al:Zr ratios. Finally, the counteranions which form are dependent on choice of precursor and Al:Zr ratio; halogenated aluminoxane anions [(MeAlO)x(Me3Al)yz(Me2AlCl)zMe]– (z = 1, 2, 3…) are observed using metal chloride complexes and under some conditions may predominate over their non-halogenated precursors [(MeAlO)x(Me3Al)yMe]–. Specifically, this halogenation process appears selective for the anions which form vs. the neutral components of MAO. Only at very high Al:Zr ratios is the same “native” anion distribution observed when using Cp2ZrCl2 when compared with Cp2ZrMe2. Together, the results suggest that the need for a large excess of MAO when using metallocene dichloride complexes is a reflection of competitive alkylation vs. ionization, the persistence of unreactive, homodinuclear ion-pairs in the case of Cp2ZrCl2, as well as a change in ion-pairing resulting from modification of the anions formed at lower Al:Zr ratios. Models for neutral precursors and anions are examined computationally. | en_US |
| dc.description.reviewstatus | Reviewed | en_US |
| dc.description.scholarlevel | Faculty | en_US |
| dc.description.sponsorship | American Chemical Society Petroleum Research Fund (49195-ND3), NSERC (Discovery, Discovery Accelerator Supplement, and Research Tools and Infrastructure grants). | en_US |
| dc.identifier.citation | Trefz, T. K., Henderson, M. A., Linnolahti, M., Collins, S. and McIndoe, J. S. (2015), Mass spectrometric characterization of methylaluminoxane-activated metallocene complexes. Chemistry A European Journal, 21: 2980–2991. | en_US |
| dc.identifier.uri | http://onlinelibrary.wiley.com/doi/10.1002/chem.201405319/abstract | |
| dc.identifier.uri | http://hdl.handle.net/1828/7946 | |
| dc.language.iso | en | en_US |
| dc.publisher | Chemistry A European Journal | en_US |
| dc.subject.department | Department of Chemistry | |
| dc.title | Mass spectrometric characterization of methylaluminoxane-activated metallocene complexes | en_US |
| dc.type | Postprint | en_US |