Rubidium superoxide

Rubidium superoxide or Rubidium hyperoxide is a compound with the formula RbO2. In terms of oxidation states, the negatively charged superoxide and positively charged rubidium give it a structural formula of (Rb+)(O2−).[2]

Rubidium superoxide
Identifiers
3D model (JSmol)
  • InChI=1S/O2.Rb/c1-2;/q-1;+1
    Key: AFEOXRVICKHWAE-UHFFFAOYSA-N
  • O=[O-].[Rb+]
Properties
O2Rb
Molar mass 117.466 g·mol−1
Appearance Bright yellow color[1]
Structure
Distorted CaC2 structure[2]
Related compounds
Other cations
 Lithium superoxide
Sodium superoxide
Potassium superoxide
Caesium superoxide
Rubidium suboxide
Rubidium oxide
Rubidium sesquioxide
Rubidium peroxide
Rubidium ozonide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Chemistry

It can be created by slowly exposing elemental rubidium to oxygen gas:[3]

Rb(s) + O2(g) → RbO2(s)

Like other alkali metal hyperoxides, crystals can also be grown in liquid ammonia.[4]

Between 280 and 360 °C, Rubidium superoxide will decompose, leaving not rubidium sesquioxide (Rb2O3), but rather rubidium peroxide (Rb2O2).[3]

RbO2 (s) → 1/2 Rb2O2(s) + 1/2 O2(g)

An even more oxygen rich compound, that of rubidium ozonide (RbO3) can be created using RbO2.[5]

Properties

Roughly speaking, RbO2 has a crystal structure similar to tetragonal calcium carbide, but is rather distorted due to the Jahn–Teller effect, which makes the crystal structure less symmetrical.[2]

RbO2 is stable in dry air, but is extremely hygroscopic.[3]

The compound has been studied as an example of magnetism arising intrinsically from the p-shell.[6] RbO2 has been predicted to be a paramagnetic Mott insulator.[7] At low temperatures, it transitions to antiferromagnetic order, with a Neel temperature of 15 K.[2]

See also

References
  1. Astuti, Fahmi; Miyajima, Mizuki; Fukuda, Takahito; Kodani, Masashi; Nakano, Takehito; Kambe, Takashi; Watanabe, Isao (2019). "Synthesis and Characterization of Magnetic Rubidium Superoxide, RbO2". Materials Science Forum. Trans Tech Publications, Ltd. 966: 237–242. doi:10.4028/www.scientific.net/msf.966.237. ISSN 1662-9752.
  2. Labhart, M.; Raoux, D.; Känzig, W.; Bösch, M. A. (1979-07-01). "Magnetic order in 2p-electron systems: Electron paramagnetic resonance and antiferromagnetic resonance in the alkali hyperoxides KO2, RbO2, and CsO2". Physical Review B. American Physical Society (APS). 20 (1): 53–70. doi:10.1103/physrevb.20.53. ISSN 0163-1829.
  3. Kraus, D. L.; Petrocelli, A. W. (1962). "The Thermal Decomposition of Rubidium Superoxide". The Journal of Physical Chemistry. American Chemical Society (ACS). 66 (7): 1225–1227. doi:10.1021/j100813a003. ISSN 0022-3654.
  4. Busch, G.; Strässler, S., eds. (1974). "Magnetische und kalorische Eigenschaften von Alkali-Hyperoxid-Kristallen". Physics of Condensed Matter. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 267–291. doi:10.1007/978-3-662-39595-0. ISBN 978-3-662-38713-9.
  5. Vol'nov, I. I.; Dobrolyubova, M. S.; Tsentsiper, A. B. (1966). "Synthesis of rubidium ozonide via rubidium superoxide". Bulletin of the Academy of Sciences, USSR Division of Chemical Science. Springer Science and Business Media LLC. 15 (9): 1611–1611. doi:10.1007/bf00848934. ISSN 0568-5230.
  6. Kováčik, Roman; Ederer, Claude (2009-10-26). "Correlation effects in p-electron magnets: Electronic structure of RbO2 from first principles". Physical Review B. American Physical Society (APS). 80 (14): 140411. arXiv:0905.3721. doi:10.1103/physrevb.80.140411. ISSN 1098-0121.
  7. Kováčik, Roman; Werner, Philipp; Dymkowski, Krzysztof; Ederer, Claude (2012-08-17). "Rubidium superoxide: A p-electron Mott insulator". Physical Review B. American Physical Society (APS). 86 (7): 075130. arXiv:1206.1423. doi:10.1103/physrevb.86.075130. ISSN 1098-0121.


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