292856-03-2Relevant academic research and scientific papers
Bis(permethylcyclopentadienyl)aluminum compounds: Precursors to [Cp*2Al]+ but not to Cp*3Al
Burns, Christopher T.,Shapiro, Pamela J.,Budzelaar, Peter H. M.,Willett, Roger,Vij, Ashwani
, p. 3361 - 3367 (2000)
Replacement of only two chloride ligands occurs when AlCl3 is reacted with 3 equiv of either Cp*Na or Cp*K, forming Cp*2AlCl (1) [Cp* = C5Me5]. This compound dissociates a chloride ion in polar solvents such as methylene chloride. Clean formation of decamethyl-aluminocenium salts could not be accomplished by abstraction of a chloride ligand from 2 with silver salts, LiB(C6F5)4, or NaB(C6F5)4. However, reaction of Cp*2AlMe (2) with B(C6F5)3 cleanly affords the salt [Cp*2Al]+[B(C6F5) 3Me]- (3). X-ray crystal structures of both 2 and 3 are reported. In the solid state, 2 exhibits a bis-dihapto ring coordination similar to that of (η2-C5H5)2AlMe. The molecular structure of 3 shows complete methyl anion abstraction from the aluminum. The decamethylaluminocenium salt is more stable in solution than its nonmethylated analogue; however, it is also considerably less active as an initiator for the cationic polymerization of isobutene.
