trans-Dichlorobis(ethylenediamine)cobalt(III) chloride
trans-Dichlorobis(ethylenediamine)cobalt(III) chloride is a salt with the formula [CoCl2(en)2]Cl (en = ethylenediamine). It is a green diamagnetic solid that is soluble in water. It is the monochloride salt of the cationic coordination complex [CoCl2(en)2]+. One chloride ion in this salt readily undergoes ion exchange but the two other chlorides are less reactive, being bound to the metal center. The more stable cis-dichlorobis(ethylenediamine)cobalt(III) chloride is also known.
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Identifiers | |
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3D model (JSmol) |
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PubChem CID |
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Properties | |
C4H16Cl3CoN4 | |
Molar mass | 285.48 g·mol−1 |
Appearance | green solid |
Melting point | decomposes |
good | |
Hazards | |
GHS pictograms | ![]() |
GHS Signal word | Warning |
GHS hazard statements |
H315, H319, H335 |
P261, P305+351+338 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
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Infobox references | |
Synthesis
The compound is synthesized by the reaction of cobalt(II) chloride and ethylenediamine in hydrochloric acid in the presence of oxygen:
- 4 CoCl2 + 8 en + 4 HCl + O2 → 4 trans-[CoCl2(en)2]Cl + 2 H2O
The initial product contains HCl, which is removed by heating. Alternatively, (carbonato)bis(ethylenediamine)cobalt(III) chloride reacts with hydrochloric acid at 10 °C to give the same species.[1]
- [Co(CO3)(en)2]Cl + 2 HCl → trans-[CoCl2(en)2]Cl + CO2 + H2O
![](../I/m/Ultraviolet-visible_spectroscopy_of_Dichlorobis(ethylenediamine)cobalt(III)_chloride.png)
Comparison of cis and trans isomers
This salt is more soluble than the cis isomer. This pair of isomers was significant in the development of the area of coordination chemistry.[2]
The trans isomer cation has idealized D2h point group symmetry, whereas the cis isomer cation has C2 symmetry.
References
- Springbørg, J.; Schaffer, C.E. "Dianionobis(Ethylenediamine)Cobalt(III) Complexes" Inorganic Syntheses, 1973; volume 14, pages 63-77. doi:10.1002/9780470132456.ch14
- Jörgensen, S.M. "Ueber Metalldiaminverbindungen" Journal für praktische Chemie (in German), 1889, volume 39, page 8. doi:10.1002/prac.18890390101