| Abstrakt: |
The compounds (R)- and rac-[1-(dimethylamino)ethyl]benzene, (R)-1 and rac-1, respectively, react quantitatively with tBuLi in a 1:1 molar ratio in pentane to give the corresponding (R)- and rac-[Li4{C6H4[CH(Me)NMe2]-2}4], (R)-2 and rac-2, respectively. The same reaction with nBuLi afforded a 1:1:1 aggregate of nBuLi, 2, and 1 according to the results of quench experiments with H2O and D2O. The 1H, 13C, and 7Li NMR spectra, as well as the single-crystal X-ray structure, reveal that (R)-2 has a unique self-assembled tetranuclear structure of two diastereoisomeric dimeric units both in solution, in non-coordinating hydrocarbon solvents, and in the solid state. Detailed information about rac-2, which, in contrast to the high solubility of (R)-2, is essentially insoluble in hydrocarbon solvents, was provided by 13C CP/MAS NMR spectra. We conclude that rac-2 is a self-assembled tetranuclear aggregate comprising a combination of two dimeric units, but in this case they are derived from the (R)- and (S)-enantiomers, respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) |
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