Alkalide

"Normal" chemistry: the case of Na⁺

Alkali metals are well known to form salts. Table salt, or sodium chloride Na⁺Cl^-, illustrates the usual role of an alkali metal such as sodium: its positive charge is balanced by a negatively charged ion in the electron configuration. Sodium was thought to always form singly charged cations until the discovery of alkalides^[2] and the same arguments apply to the remainder of the alkali metals.

Scope of alkalides

Known alkalides include electrides.

Examples

A typical alkalide is the sodium natride salt [Na(sodium hydride"^[3].

Normally, alkalides are thermally labile due to the high reactivity of the alkalide anion, which is theoretically able to break most cryptand. The introduction of a special cryptand ligand has allowed the isolation of kalide and natrides that are stable at room temperature.^[4]

References

1. ^ ^{a b} Redko MY, Huang RH, Jackson JE, Harrison JF, Dye JL. (2003). Barium azacryptand sodide, the first alkalide with an alkaline Earth cation, also contains a novel dimer, (Na(2))(2-). J Am Chem Soc 125(8):2259-63.
2. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
3. ^ Redko MY, Vlassa M, Jackson JE, Misiolek AW, Huang RH, Dye JL.(2002). "Inverse sodium hydride": a crystalline salt that contains H(+) and Na(-). J Am Chem Soc 124(21):5928-9.
4. ^ Kim, J.; Ichimura, A. S.; Huang, R. H.; Redko, M.; Phillips, R. C.; Jackson, J. E. and Dye, J. L. (1999). Crystalline Salts of Na^- and K^- (Alkalides) that Are Stable at Room Temperature. J Am Chem Soc 121:10666-10667.