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

Armstrong, David R. and Kennedy, Alan R. and Mulvey, Robert E. and Robertson, Stuart D. (2013) A hetero-alkali-metal version of the utility amide LDA : lithium-potassium diisopropylamide. Dalton Transactions, 42 (10). pp. 3704-3711. ISSN 1477-9234

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    Abstract

    Designed to extend the synthetically important alkali-metal diisopropylamide [(NPr2)-Pr-i; 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 Li2KN3 heterocycle, with TMEDA only solvating the largest of the alkali-metals, with the two-coordinate lithium atoms being close to linearity [161.9(2)degrees]. 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.