A hetero-alkali-metal version of the utility amide LDA: lithium-potassium diisopropylamide.

Designed to extend the synthetically important alkali-metal diisopropylamide [N(i)Pr(2); DA] class of compounds, the first example of a hetero-alkali-metallic complex of DA has been prepared as a partial TMEDA solvate. Revealed by an X-ray crystallographic study, its structure exists as a discrete lithium-rich trinuclear Li(2)KN(3) heterocycle, with TMEDA only solvating the largest of the alkali-metals, with the two-coordinate lithium atoms being close to linearity [161.9(2)°]. A variety of NMR spectroscopic studies, including variable temperature and DOSY NMR experiments, suggests that this new form of LDA maintains its integrity in non-polar hydrocarbon solution. This complex thus represents a rare example of a KDA molecule which is soluble in non-polar medium without the need for excessive amounts of solubilizing Lewis donor being added.

Citation

David R Armstrong, Alan R Kennedy, Robert E Mulvey, Stuart D Robertson. A hetero-alkali-metal version of the utility amide LDA: lithium-potassium diisopropylamide. Dalton transactions (Cambridge, England : 2003). 2013 Mar 14;42(10):3704-11

PMID: 23299468

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