OBSERVATION OF HYPERVALENT CLI6 BY KNUDSEN-EFFUSION MASS-SPECTROMETRY

BECAUSE of the unusual geometry, bonding and reactivity of some lithiated molecules, they (polylithiated hydrocarbons in particular) have attracted interest from organic, organometallic and theoretical chemists 1-7. 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. Her I report the observation of CLi6, which forms in the gas phase over solid Li2C2 and is identified by Knudsen-effusion mass spectrometry 8. 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.