r ac -Me 2 Si(2-Me-4- t- Bu-C 5 H 2 ) 2 ZrMe + : An Alkyl Zirconocenium Cation Stabilized by Steric Shielding against Interaction with Ancillary Ligands
2005; American Chemical Society; Volume: 24; Issue: 5 Linguagem: Inglês
10.1021/om049139z
ISSN1520-6041
AutoresLars Schröder, Hans‐Herbert Brintzinger, Dmitrii E. Babushkin, David M. Fischer, Rolf Mülhaupt,
Tópico(s)Synthesis and characterization of novel inorganic/organometallic compounds
ResumoThe sterically shielded cation rac-Me2Si(2-Me-4-t-Bu-C5H2)2ZrMe+, generated by reaction of rac-Me2Si(2-Me-4-t-Bu-C5H2)2ZrMe2 with methylalumoxane (MAO) or with dimethylanilinium or trityl perfluorotetraphenylborate, differs from other, more open zirconocene methyl cations in that it does not form the symmetric AlMe3 adduct rac-Me2Si(2-Me-4-t-Bu-C5H2)2Zr(μ-Me)2AlMe2+. Instead, the unsymmetric ternary adduct rac-Me2Si(2-Me-4-t-Bu-C5H2)2ZrMe(μ-Me)AlMe3−NMe2Ph+ is formed in the presence of dimethylaniline and trimethylaluminum. UV/vis and 1H NMR characteristics of hydrocarbon solutions containing rac-Me2Si(2-Me-4-t-Bu-C5H2)2ZrMe+···B(C6F5)4- or rac-Me2Si(2-Me-4-t-Bu-C5H2)2ZrMe+···MAOMe- indicate that cation−anion association in these ion pairs is unusually weak.
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