Abstract:
In 1984 Tsueno Imamoto published a paper about the binary mixtures CeCl3/RLi (R = nBu,
tBu) and their use in carbon-carbon-bond formation with various carbonyl compounds. The
exact structure of these reagents, however, remained a mystery since then.
These mixtures were studied via NMR experiments including 7Li NMR spectroscopy.
Moreover, a procedure was developed to isolate organolithium/lanthanide complexes from
these reactions. For example, Li3Ln(nBu)6(thf)4 (Ln = Sc, Y, La, Ce, Lu) and
[Ce(tBu)4][Li(thf)4] could be accessed and fully characterized. The crucial part of these
procedures is a seamless low-temperature syntheses and crystallization sequence, since the
products are thermally very unstable.
The working techniques were then applied to isolate the MAO species [(AlMe2)2O(thf)]2 from
the simple reaction of AlMe3 and water in THF. MAO is the most important co-catalyst in
commercial α-olefin polymerization. Although, its structure has remained elusive so far, many
model complexes have been synthesized. These complexes, however, require laborious
pathways or exotic precursors.
Lastly, the field of organolanthanide complexes was revisited. Using the aza crown (1,4,7-
Trimethyl-1,4,7-triazacyclononane = Me3TACN) the complexes (Me3TACN)Ln(nBu)3 (Ln =
La, Sm) could be synthesized as the first terminal n-butyl lanthanide complexes, that contain
no other metal. Further, the hitherto elusive lanthanum neosilyl complex [Li(thf)4]
[La(CH2SiMe3)4(thf)] was isolated and fully characterized.
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