Cobalt compounds

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Cobalt compounds are chemical compounds formed by cobalt with other elements.

Contents

Inorganic compounds

Halides

Magenta coloured CoCl2*6H2O Cobalt(II)-chloride-hexahydrate-sample.jpg
Magenta coloured CoCl2·6H2O

Many halides of cobalt(II) are known.e cobalt(II) fluoride (CoF2) which is a pink solid, cobalt(II) chloride (CoCl2) which is a blue solid, cobalt(II) bromide (CoBr2) which is a green solid, and cobalt(II) iodide (CoI2) which is a blue-black solid. In addition to the anhydrous forms, these cobalt halides also have hydrates. Anhydrous cobalt(II) chloride is blue, while the hexahydrate is magenta in colour. [1] Because the color change of cobalt(II) chloride in different hydrates, it can be used to manufacture color-changing silica gel.

Anhydrous cobalt halides react with nitric oxide at 70~120 °C to generate [Co(NO)2X]2 (X = Cl, Br or I). The complex of cobalt halides and triethylphosphine ((C2H5)3P) can absorb nitric monoxide in benzene to form the diamagnetic material Co(NO)X2(P(C2H5)3) [2]

In the reaction Co3+
 + e− → Co2+
, the potential is +1.92 V, which is higher than that of Cl2 to Cl− (+1.36 V). Therefore, the interaction of Co3+ with Cl− produces Co2+ and releases chlorine gas. The potential from F2 to F− is as high as +2.87 V, and cobalt(III) fluoride (CoF3) can exist stably. It is a fluorinated reagent and reacts violently with water. [3]

Oxides and hydroxides

Cobalt(II,III) oxide Cobalt(II,III) oxide.jpg
Cobalt(II,III) oxide

Cobalt can form various oxides, such as CoO, Co2O3 and Co3O4. Co3O4, at 950 °C, decomposes to CoO. [4]

Soluble cobalt salts react with sodium hydroxide to obtain cobalt(II) hydroxide (Co(OH)2): [5]

Co(NO3)2 + 2 NaOH → Co(OH)2↓ + 2 NaNO3

Cobalt(II) hydroxide can be oxidized to the Co(III) compound CoO(OH) under alkaline conditions.

Pnictogenides

Cobalt(II) nitrate hexahydrate Cobalt(II) Nitrate.jpg
Cobalt(II) nitrate hexahydrate

Cobalt powder reacts with ammonia to form two kinds of nitrides, Co2N and Co3N. Cobalt reacts with phosphorus or arsenic to form Co2P, CoP, [2] CoP2, [6] CoAs2 and other substances. [2] The former three compounds are of interest as catalysts for water electrolysis. [6] [7] [8]

Cobalt(II) azide (Co(N3)2) is another binary compound of cobalt and nitrogen that can explode when heated. Cobalt(II) and azide can form Co(N
3)2−
4 complexes. [9] Cobalt pentazolide Co(N5)2 was discovered in 2017, and it exists in the form of the hydrate [Co(H2O)4(N5)2]·4H2O. It decomposes at 50~145 °C to form cobalt(II) azide, becoming anhydrous and releasing nitrogen, and exploding when heated further. This compound can be obtained by reacting (N5)6(H3O)3(NH4)4Cl [10] or Na(H2O)(N5)]·2H2O [11] and [Co(H2O)6](NO3)2 at room temperature. Hydrogen bonding of water stabilizes this molecule. [11]

Cobalt can easily react with nitric acid to form cobalt(II) nitrate Co(NO3)2. Cobalt(II) nitrate exists in the anhydrous form and the hydrate form, of which the hexahydrate is the most common. Cobalt nitrate hexahydrate (Co(NO3)2·6H2O) is a red deliquescence crystal that is easily soluble in water, [12] and its molecule contains cobalt(II) hydrated ions ([Co(H2O)6]2+) and free nitrate ions. [13] It can be obtained by precipitation from solution.

Coordination compounds

As for all metals, molecular compounds and polyatomic ions of cobalt are classified as coordination complexes, that is, molecules or ions that contain cobalt linked to one or more ligands. These can be combinations of a potentially infinite variety of molecules and ions, such as:

These attached groups affect the stability of oxidation states of the cobalt atoms, according to general principles of electronegativity and of the hardness–softness. For example, Co3+ complexes tend to have ammine ligands. Because phosphorus is softer than nitrogen, phosphine ligands tend to feature the softer Co2+ and Co+, an example being tris(triphenylphosphine)cobalt(I) chloride (P(C
6H
5)
3)
3CoCl). The more electronegative (and harder) oxide and fluoride can stabilize Co4+ and Co5+ derivatives, e.g. caesium hexafluorocobaltate(IV) (Cs2CoF6) and potassium percobaltate (K3CoO4). [17]

Alfred Werner, a Nobel-prize winning pioneer in coordination chemistry, worked with compounds of empirical formula [Co(NH
3)
6]3+
. One of the isomers determined was cobalt(III) hexammine chloride. This coordination complex, a typical Werner-type complex, consists of a central cobalt atom coordinated by six ammine orthogonal ligands and three chloride counteranions. Using chelating ethylenediamine ligands in place of ammonia gives tris(ethylenediamine)cobalt(III) ([Co(en)
3]3+
), which was one of the first coordination complexes to be resolved into optical isomers. The complex exists in the right- and left-handed forms of a "three-bladed propeller". This complex was first isolated by Werner as yellow-gold needle-like crystals. [18] [19]

Organic compounds

Structure of Vitamin B12 Cobalamin skeletal.svg
Structure of Vitamin B12

Vitamin B12 is a cobalt-centered organic biomolecule, soluble in water, and involved in the methylation and synthesis of nucleic acid and neurotransmitter. [20] The main source is the offal or meat of herbivorous animals. [21]

Dicobalt octacarbonyl (Co2(CO)8) is an orange-red crystal with two isomers in solution: [22]

Co2(CO)8NoCo-Co.png

It reacts with hydrogen or sodium to form HCo(CO)4 or NaCo(CO)4. It is a catalyst in carbonylation and hydrosilylation reactions. [23]

Cobaltocene (Co(C5H5)2) is a cyclopentadiene complex of cobalt. It has 19 valence electrons and is easily oxidized to Co(C
5H
5)+
2 with a stable structure of 18 electrons by reaction. [24] It is a structural analog to ferrocene, with cobalt in place of iron. Cobaltocene is much more sensitive to oxidation than ferrocene. [25]

See also

Related Research Articles

<span class="mw-page-title-main">Copper(II) nitrate</span> Chemical compound

Copper(II) nitrate describes any member of the family of inorganic compounds with the formula Cu(NO3)2(H2O)x. The hydrates are blue solids. Anhydrous copper nitrate forms blue-green crystals and sublimes in a vacuum at 150-200 °C. Common hydrates are the hemipentahydrate and trihydrate.

<span class="mw-page-title-main">Cobalt(II) chloride</span> Chemical compound

Cobalt(II) chloride is an inorganic compound, a salt of cobalt and chlorine, with the formula CoCl
2. The compound forms several hydrates CoCl
2·nH
2O, for n = 1, 2, 6, and 9. Claims of the formation of tri- and tetrahydrates have not been confirmed. The anhydrous form is a blue crystalline solid; the dihydrate is purple and the hexahydrate is pink. Commercial samples are usually the hexahydrate, which is one of the most commonly used cobalt salts in the lab.

<span class="mw-page-title-main">Cobalt(III) fluoride</span> Chemical compound

Cobalt(III) fluoride is the inorganic compound with the formula CoF3. Hydrates are also known. The anhydrous compound is a hygroscopic brown solid. It is used to synthesize organofluorine compounds.

<span class="mw-page-title-main">Iron(III) oxide-hydroxide</span> Hydrous ferric oxide (HFO)

Iron(III) oxide-hydroxide or ferric oxyhydroxide is the chemical compound of iron, oxygen, and hydrogen with formula FeO(OH).

<span class="mw-page-title-main">Scandium nitrate</span> Chemical compound

Scandium(III) nitrate, Sc(NO3)3, is an ionic compound. It is an oxidizer, as all nitrates are. The salt is applied in optical coatings, catalysts, electronic ceramics and the laser industry.

<span class="mw-page-title-main">Zinc nitrate</span> Chemical compound

Zinc nitrate is an inorganic chemical compound with the formula Zn(NO3)2. This colorless, crystalline salt is highly deliquescent. It is typically encountered as a hexahydrate Zn(NO3)2·6H2O. It is soluble in both water and alcohol.

<span class="mw-page-title-main">Iron(III) nitrate</span> Chemical compound

Iron(III) nitrate, or ferric nitrate, is the name used for a series of inorganic compounds with the formula Fe(NO3)3.(H2O)n. Most common is the nonahydrate Fe(NO3)3.(H2O)9. The hydrates are all pale colored, water-soluble paramagnetic salts.

The chemical element nitrogen is one of the most abundant elements in the universe and can form many compounds. It can take several oxidation states; but the most common oxidation states are -3 and +3. Nitrogen can form nitride and nitrate ions. It also forms a part of nitric acid and nitrate salts. Nitrogen compounds also have an important role in organic chemistry, as nitrogen is part of proteins, amino acids and adenosine triphosphate.

<span class="mw-page-title-main">Chromium compounds</span> Chemical compounds containing chromium

Chromium compounds are compounds containing the element chromium (Cr). Chromium is a member of group 6 of the transition metals. The +3 and +6 states occur most commonly within chromium compounds, followed by +2; charges of +1, +4 and +5 for chromium are rare, but do nevertheless occasionally exist.

<span class="mw-page-title-main">Cobalt(II) nitrate</span> Chemical compound

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.

<span class="mw-page-title-main">Cobalt(III) nitrate</span> Chemical compound

Cobalt(III) nitrate is an inorganic compound with the chemical formula Co(NO3)3. It is a green, diamagnetic solid that sublimes at ambient temperature.

<span class="mw-page-title-main">Cerium nitrates</span> Chemical compound

Cerium nitrate refers to a family of nitrates of cerium in the +3 or +4 oxidation state. Often these compounds contain water, hydroxide, or hydronium ions in addition to cerium and nitrate. Double nitrates of cerium also exist.

Cobalt(III) chloride or cobaltic chloride is an unstable and elusive compound of cobalt and chlorine with formula CoCl
3. In this compound, the cobalt atoms have a formal charge of +3.

Indium(III) nitrate is a nitrate salt of indium which forms various hydrates. Only the pentahydrate has been crystallographically verified. Other hydrates are also reported in literature, such as the trihydrate.

<span class="mw-page-title-main">Transition metal nitrate complex</span> Compound of nitrate ligands

A transition metal nitrate complex is a coordination compound containing one or more nitrate ligands. Such complexes are common starting reagents for the preparation of other compounds.

<span class="mw-page-title-main">Europium compounds</span> Chemical compounds

Europium compounds are compounds formed by the lanthanide metal europium (Eu). In these compounds, europium generally exhibits the +3 oxidation state, such as EuCl3, Eu(NO3)3 and Eu(CH3COO)3. Compounds with europium in the +2 oxidation state are also known. The +2 ion of europium is the most stable divalent ion of lanthanide metals in aqueous solution. Many europium compounds fluoresce under ultraviolet light due to the excitation of electrons to higher energy levels. Lipophilic europium complexes often feature acetylacetonate-like ligands, e.g., Eufod.

Lutetium compounds are compounds formed by the lanthanide metal lutetium (Lu). In these compounds, lutetium generally exhibits the +3 oxidation state, such as LuCl3, Lu2O3 and Lu2(SO4)3. Aqueous solutions of most lutetium salts are colorless and form white crystalline solids upon drying, with the common exception of the iodide. The soluble salts, such as nitrate, sulfate and acetate form hydrates upon crystallization. The oxide, hydroxide, fluoride, carbonate, phosphate and oxalate are insoluble in water.

Carbonate nitrates are mixed anion compounds containing both carbonate and nitrate ions.

<span class="mw-page-title-main">Cobalt(II) perchlorate</span> Chemical compound

Cobalt(II) perchlorate is an inorganic chemical compound with the formula Co(ClO4)2·nH2O (n = 0,6). The pink anhydrous and red hexahydrate forms are both hygroscopic solids.

References

  1. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 1119–1120. ISBN   978-0-08-037941-8.
  2. 1 2 3 申泮文 等. 无机化学丛书 第九卷 锰分族 铁系 铂系. 科学出版社, 2017. ISBN 9787030305459
  3. ↑ Holleman, A. F.; Wiberg, E.; Wiberg, N. (2007). "Cobalt". Lehrbuch der Anorganischen Chemie (in German) (102nd ed.). de Gruyter. pp. 1146–1152. ISBN 978-3-11-017770-1.
  4. ↑ US 4389339 Archived 2019-07-01 at the Wayback Machine , James, Leonard E.; Crescentini, Lamberto & Fisher, William B., "Process for making a cobalt oxide catalyst"
  5. ↑ O. Glemser "Cobalt(II) Hydroxide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1521.
  6. 1 2 Jianmei Wang; Zhen Liu; Yiwei Zheng; Liang Cui; Wenrong Yang; Jingquan Liu (19 October 2017) [22 September 2017]. "Recent advances in cobalt phosphide based materials for energy-related applications". Journal of Materials Chemistry A. 5 (44). Royal Society of Chemistry: 22913–22932. doi:10.1039/c7ta08386f.
  7. ↑ Popczun, Eric J.; Read, Carlos G.; Roske, Christopher W.; Lewis, Nathan S.; Schaak, Raymond E. (11 April 2014) [May 19, 2014]. "Highly Active Electrocatalysis of the Hydrogen Evolution Reaction by Cobalt Phosphide Nanoparticles". Angewandte Chemie International Edition. 53 (21): 5427–5430. doi:10.1002/anie.201402646. PMID   24729482.
  8. ↑ Doan-Nguyen, Vicky V. T.; Sen Zhang; Trigg, Edward B.; Agarwal, Rahul; Jing Li; Dong Su; Winey, Karen I.; Murray, Christopher B. (July 14, 2015) [April 13, 2015]. "Synthesis and X‑ray Characterization of Cobalt Phosphide (Co2P) Nanorods for the Oxygen Reduction Reaction" (PDF). ACS Nano. 9 (8): 8108–8115. doi:10.1021/acsnano.5b02191. OSTI   1213384. PMID   26171574.
  9. ↑ Senise, Paschoal (1959). "On the Reaction between Cobalt(II) and Azide Ions in Aqueous and Aqueous-organic Solutions1". Journal of the American Chemical Society. 81 (16): 4196–4199. doi:10.1021/ja01525a020.
  10. ↑ Zhang, Chong; Yang, Chen; Hu, Bingcheng; Yu, Chuanming; Zheng, Zhansheng; Sun, Chengguo (2017). "A Symmetric Co(N5 )2 (H2 O)4 ⋅4 H2 O High-Nitrogen Compound Formed by Cobalt(II) Cation Trapping of a Cyclo-N5− Anion". Angewandte Chemie International Edition. 56 (16): 4512–4514. doi:10.1002/anie.201701070. PMID   28328154.
  11. 1 2 Xu, Yuangang; Wang, Qian; Shen, Cheng; Lin, Qiuhan; Wang, Pengcheng; Lu, Ming (2017). "A series of energetic metal pentazolate hydrates". Nature. 549 (7670): 78–81. Bibcode:2017Natur.549...78X. doi:10.1038/nature23662. PMID   28847006. S2CID   4459874.
  12. ↑ Donaldson, John Dallas; Beyersmann, Detmar (2005). "Cobalt and Cobalt Compounds". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a07_281.pub2. ISBN   9783527303854.
  13. ↑ Prelesnik, P. V.; Gabela, F.; Ribar, B.; Krstanovic, I. (1973). "Hexaaquacobalt(II) nitrate". Cryst. Struct. Commun. 2 (4): 581–583.
  14. 1 2 3 4 5 6 McCutcheon, Thomas P.; Schuele, William J. (1953). "Complex Acids of Cobalt and Chromium. The Green Carbonatocobalt(III) Anion*". Journal of the American Chemical Society. 75 (8): 1845–1846. doi:10.1021/ja01104a019.
  15. ↑ Bauer, H. F.; Drinkard, W. C. (1960). "A General Synthesis of Cobalt(III) Complexes; A New Intermediate, Na3[Co(CO3)3]·3H2O". Journal of the American Chemical Society. 82 (19): 5031–5032. doi:10.1021/ja01504a004.
  16. ↑ Tafesse, Fikru; Aphane, Elias; Mongadi, Elizabeth (2010). "Determination of the structural formula of sodium tris-carbonatocobaltate(III), Na3[Co(CO3)3]·3H2O by thermogravimetry". Journal of Thermal Analysis and Calorimetry. 102: 91–97. doi:10.1007/s10973-009-0606-2. S2CID   97142236.
  17. ↑ Holleman, A. F.; Wiberg, E.; Wiberg, N. (2007). "Cobalt". Lehrbuch der Anorganischen Chemie (in German) (102nd ed.). de Gruyter. pp. 1146–1152. ISBN   978-3-11-017770-1.
  18. ↑ Werner, A. (1912). "Zur Kenntnis des asymmetrischen Kobaltatoms. V". Chemische Berichte . 45: 121–130. doi:10.1002/cber.19120450116.
  19. ↑ Gispert, Joan Ribas (2008). "Early Theories of Coordination Chemistry". Coordination chemistry. Wiley. pp. 31–33. ISBN   978-3-527-31802-5. Archived from the original on 2016-05-05. Retrieved 2015-06-27.
  20. ↑ Miller, Ariel; Korem, Maya; Almog, Ronit; Galboiz, Yanina (2005). "Vitamin B12, demyelination, remyelination and repair in multiple sclerosis". Journal of the Neurological Sciences. 233 (1–2): 93–97. doi:10.1016/j.jns.2005.03.009. PMID   15896807. S2CID   6269094.
  21. ↑ 陈辉．现代营养学．北京：化学工业出版社，2005：76
  22. ↑ Sweany, Ray L.; Brown, Theodore L. (1977). "Infrared spectra of matrix-isolated dicobalt octacarbonyl. Evidence for the third isomer". Inorganic Chemistry. 16 (2): 415–421. doi:10.1021/ic50168a037.
  23. ↑ Charles M. Starks; Charles Leonard Liotta; Marc Halpern (1994). Phase-transfer catalysis: fundamentals, applications, and industrial perspectives. Springer. pp. 600–. ISBN   978-0-412-04071-9 . Retrieved 2011-05-16.
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  25. ↑ James E. House (2008). Inorganic chemistry. Academic Press. pp. 767–. ISBN   978-0-12-356786-4 . Retrieved 2011-05-16.
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