Alkalides

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As alkalide refers to chemical compounds in which an alkali metal as an anion is present. You are extremely reactive. The corresponding anions are sodium , potassium , rubid and caesid . Anions of lithium are currently (as of 2014) not yet known.

presentation

A key aspect in the preparation of alkalides is the use of crown ethers or cryptands to complex the alkali metal cations. The first such compound was made in 1974 by James L. Dye and others in the form Na + (C222) Na - (C222 = 2.2.2-cryptand). The synthesis is usually carried out by dissolving the corresponding alkali metal in liquid ammonia or an alkylamine in the presence of a suitable cryptand or crown ether. As a rule, the synthesis takes place below −20 ° C. In 1999, however, the first natrides and potashes could be produced, which are stable at room temperature. Electrides can be represented in a similar way , analogous compounds in which the anion is an electron .

Further examples

Examples of further unusual alkali compounds are barium sodium, first presented in 2003, the first compound of an alkali to contain an alkaline earth metal as a cation . In 2006, one-dimensional zigzag chains could be produced from a lithium caesid of the formula Li + (C211) Cs - (C211 = 2.1.1-cryptand).

use

Alkalides are often used in situ . William J. Evans et al. Could show for the first time in 2013 that the use of metallic potassium in diethyl ether in the presence of 18-crown-6 at −35 ° C under argon for the synthesis of compounds of praseodymium , gadolinium , terbium and lutetium in the oxidation state +2 is possible. He was also able to present uranium in the +2 oxidation state for the first time by reducing a uranium (III) compound in the presence of 2.2.2-cryptand with potassium graphite (KC 8 ) at room temperature in tetrahydrofuran under argon.

Individual evidence

  1. ↑ a b James L. Dye: Recent Developments in the Synthesis of Alkalides and Electrides. In: J. Phys. Chem. 1984, 88, pp. 3842-3846.
  2. ↑ Rui H. Huang, DL Ward, JL Dye: Alkali-Metal-Anion Dimers and Chains in Alkalide Structures. In: J. Am. Chem. Soc. 1989, 111, pp. 5707-5708.
  3. ↑ Rui H. Huang, Judith L. Eglin, Song Z. Huang, Lauren EH McMills, James L. Dye: Complexation of the Cations of Six Alkalides and an Electride by Mixed Crown Ethers. In: J. Am. Chem. Soc. 1993, 115, pp. 9542-9546.
  4. ↑ Jineun Kim, Andrew S. Ichimura, Rui H. Huang, Mikhail Redko, Richard C. Phillips, James E. Jackson, James L. Dye: Crystalline Salts of Na - and K - (Alkalides) that Are Stable at Room Temperature. In: J. Am. Chem. Soc. 1999, 121, pp. 10666-10667.
  5. ↑ Mikhail Y. Redko, Rui H. Huang, James E. Jackson, James F. Harrison, James L. Dye: Barium Azacryptand Sodide, the First Alkalide with an Alkaline Earth Cation, Also Contains a Novel Dimer, (Na 2 ) 2 - . In: J. Am. Chem. Soc. 2003, 125, pp. 2259-2263.
  6. ↑ Andrew S. Ichimura, Rui H. Huang, Qingshan Xie, Philip Morganelli, Amy Burns, James L. Dye: One-Dimensional Zigzag Chains of Cs - . In: J. Phys. Chem. B 2006, 110, pp. 12293-12301.
  7. ^ Matthew R. MacDonald, Jefferson E. Bates, Joseph W. Ziller, Filipp Furche , William J. Evans: Completing the Series of +2 Ions for the Lanthanide Elements: Synthesis of Molecular Complexes of Pr 2+ , Gd 2+ , Tb 2+ , and Lu 2+ . In: J. Am. Chem. Soc. 2013, 135, pp. 9857-9868.
  8. ^ Matthew R. MacDonald, Megan E. Fieser, Jefferson E. Bates, Joseph W. Ziller, Filipp Furche , William J. Evans: Identification of the +2 Oxidation State for Uranium in a Crystalline Molecular Complex, [K (2.2.2 -Cryptand)] [(C 5 H 4 SiMe 3 ) 3 U]. In: J. Am. Chem. Soc. 2013, 135, pp. 13310-13313.