Colonel William A. Phillips

Cobalt nitrate is the inorganic compound with the formula Co(NO3)2.xH2O. It is cobalt(II)'s salt. The most common form is the hexahydrate Co(NO3)2·6H2O, which is a red-brown deliquescent salt that is soluble in water and other polar solvents.[2]

Composition and structures

As well as the anhydrous compound Co(NO3)2, several hydrates of cobalt(II) nitrate exist. These hydrates have the chemical formula Co(NO3)2·nH2O, where n = 0, 2, 4, 6.

Anhydrous cobalt(II) nitrate adopts a three-dimensional polymeric network structure, with each cobalt(II) atom approximately octahedrally coordinated by six oxygen atoms, each from a different nitrate ion. Each nitrate ion coordinates to three cobalts.[3] The dihydrate is a two-dimensional polymer, with nitrate bridges between Co(II) centres and hydrogen bonding holding the layers together.[4] The tetrahydrate consists of discrete, octahedral [(H2O)4Co(NO3)2] molecules. The hexahydrate is better described as hexaaquacobalt(II) nitrate, [Co(OH2)6][NO3]2, as it consists of discrete [Co(OH2)6]2+ and [NO3]− ions.[5] Above 55 °C, the hexahydrate converts to the trihydrate and at higher temperatures to the monohydrate.[2]

  • Co(NO3)2
    Co(NO3)2
  • Co(NO3)2·2H2O
    Co(NO3)2·2H2O
  • Co(NO3)2·4H2O
    Co(NO3)2·4H2O
  • Co(NO3)2·6H2O
    Co(NO3)2·6H2O

Uses and reactions

It is commonly reduced to metallic high purity cobalt.[2] It can be absorbed on to various catalyst supports for use in Fischer–Tropsch catalysis.[6] It is used in the preparation of dyes and inks.[7]

Cobalt(II) nitrate is a common starting material for the preparation of coordination complexes such as cobaloximes,[8] carbonatotetraamminecobalt(III),[9] and others.[10]

Production

The hexahydrate is prepared treating metallic cobalt or one of its oxides, hydroxides, or carbonate with nitric acid:

Co + 4 HNO3 + 4 H2O → Co(H2O)6(NO3)2 + 2 NO2
CoO + 2 HNO3 + 5 H2O → Co(H2O)6(NO3)2
CoCO3 + 2 HNO3 + 5 H2O → Co(H2O)6(NO3)2 + CO2

References

  1. ^ Perrys' Chem Eng Handbook, 7th Ed
  2. ^ a b c John Dallas Donaldson, Detmar Beyersmann, "Cobalt and Cobalt Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a07_281.pub2
  3. ^ Tikhomirov, G. A.; Znamenkov, K. O.; Morozov, I. V.; Kemnitz, E.; Troyanov, S. I. (2002). "Anhydrous Nitrates and Nitrosonium Nitratometallates of Manganese and Cobalt, M(NO3)2, NO[Mn(NO3)3], and (NO)2[Co(NO3)4]: Synthesis and Crystal Structure". Z. anorg. allg. Chem. 628 (1): 269–273. doi:10.1002/1521-3749(200201)628:1<269::AID-ZAAC269>3.0.CO;2-P.
  4. ^ Ribár, B.; Milinski, N.; Herak, R.; Krstanovič, I.; Djurič, S. (1976). "The Crystal Structure of Cobalt Nitrate Dihydrate, Co(NO3)2·2H2O". Zeitschrift für Kristallographie. 144 (1–6): 133–138. Bibcode:1976ZK....144..133R. doi:10.1524/zkri.1976.144.1-6.133.
  5. ^ Prelesnik, P. V.; Gabela, F.; Ribar, B.; Krstanovic, I. (1973). "Hexaaquacobalt(II) nitrate". Cryst. Struct. Commun. 2 (4): 581–583.
  6. ^ Ernst B, Libs S, Chaumette P, Kiennemann A. Appl. Catal. A 186 (1-2): 145-168 1999
  7. ^ Lewis, Richard J., Sr. (2002). Hawley's Condensed Chemical Dictionary (14th Edition). John Wiley & Sons. http://www.knovel.com/knovel2/Toc.jsp?BookID=704&VerticalID=0
  8. ^ Schrauzer, G. N. (1968). Bis(Dimethylglyoximato)Cobalt Complexes: ("Cobaloximes"). Inorganic Syntheses. pp. 61–70. doi:10.1002/9780470132425.ch12. ISBN 9780470132425.
  9. ^ Schlessinger, G. (1960). "Carbonatotetramminecobalt(III) Nitrate". Inorganic Syntheses. 6: 173–175. doi:10.1002/9780470132371.ch55. ISBN 9780470132371.
  10. ^ Hargens, Robert D.; Min, Woonza; Henney, Robert C. (1973). "Bis(ethylenediamine)sulfito Complexes of Cobalt(III)". Inorganic Syntheses. Inorganic Syntheses. pp. 77–81. doi:10.1002/9780470132456.ch15. ISBN 9780470132456.
source: https://en.wikipedia.org/wiki/Cobalt(II)_nitrate