Carbonatobis(ethylenediamine)cobalt(III) chloride is a salt with the formula [CoCO<sub>3</sub>(en)<sub>2</sub>]Cl (en = ethylenediamine). It is a red diamagnetic solid that is soluble in water. It is the monochloride salt of a cationic carbonate complex [CoCO<sub>3</sub>(en)<sub>2</sub>]<sup>+</sup>. The chloride ion in this salt readily undergoes ion exchange. The compound is synthesized by the oxidation of a mixture of cobalt(II) chloride, lithium hydroxide, and ethylenediamine in the presence of carbon dioxide:
The cationic complex is octahedral with C<sub>2</sub> symmetry.
The carbonato ligand is readily replaced upon acid hydrolysis. Derivatives include the following complexes: cis- and trans-[CoCl<sub>2</sub>(en)<sub>2</sub>]<sup>+</sup>, cis-[Co(OH)(H<sub>2</sub>O)<sub>3</sub>(en)<sub>2</sub>]<sup>2+</sup>, cis-[Co(OH<sub>2</sub>)<sub>2</sub>(en)<sub>2</sub>]<sup>+</sup>, and cis-[Co(NO<sub>2</sub>)<sub>2</sub>(en)<sub>2</sub>]<sup>+</sup>. Reaction with trifluoromethanesulfonic acid (HOTf) gives [Co(OTf)<sub>2</sub>(en)<sub>2</sub>]OTf.