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Observation of hypervalent CLi6 by Knudsen-effusion mass spectrometry


BECAUSE of the unusual geometry, bonding and reactivity of some lithiated molecules, they (poly lithiated hydrocarbons in particular) have attracted interest from organic, organometallic and theoretical chemists1–7. Calculations by Schleyer et al.3 have predicted that the hypervalent carbon-lithium molecules CLi5 and CLi6 should be stable with respect to dissociation to CLi4 and Li2. Here I report the observation of CLi6, which forms in the gas phase over solid Li2C2 and is identified by Knudsen-effusion mass spectrometry8. I confirm that the dissociation reaction above is significantly endothermic, indicating that carbon can expand its octet of electrons to form this relatively stable molecule.

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Kudo, H. Observation of hypervalent CLi6 by Knudsen-effusion mass spectrometry. Nature 355, 432–434 (1992).

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