Reactions of L2Zr(NMe2)2 with Me3Al and PhCCH: synthesis and structural characterization of new zirconium carborane complexes [L2=Me2Si(C9H6)(C2B10H10) and Me2C(C5H4)(C2B10H10)]

Reaction of [η5:σ-Me2Si(C9H6)(C2B10H10)]Zr(NMe2)2 with excess Me3Al in toluene gave [η5:σ-Me2Si(C9H6)(C2B10H10)]Zr(μ-Me)2AlMe2(NMe2) (2). 2 is inactive toward ethylene, but shows a very high activity in ethylene polymerization upon activation with modified methylalumoxane. Recrystallization of 2 from THF/toluene afforded {[η5:σ-Me2Si(C9H6)(C2B10H10)]Zr}2(μ-O){μ-N[AlMe2(THF)]} (3). Treatment of [η5:σ-Me2C(C5H4)(C2B10H10)]Zr(NMe2)2 with two equivalents of PhCCH produced, after recrystallization from THF/toluene, {[η5:σ-Me2C(C5H4)(C2B10H10)]Zr(NMe2)}2{η2:η2-(PhCCCCPh)} (5). They were characterized by various spectroscopic data and elemental analyses. Compounds 3 and 5 were further confirmed by single-crystal X-ray analyses.