In acidic aqueous solution, the complex trans-[Co(en)₂Cl₁]²⁺(aq) undergoes the following substitution reaction:
trans-[Co(en)₁Cl₂]⁺(aq) + H₂O(l) → trans-[Co(en)₂(H₂O)Cl]²⁺(aq) + Cl^–(aq)
The reaction is first order in trans-[Co(en)₂Cl₂]⁺(aq), and the rate constant at 25°C is 3.2×10^–5 s^–1.
(d) Is the reaction product chiral or achiral? Explain.

Key Concepts

Chirality

Chirality refers to the geometric property of a molecule that makes it non-superimposable on its mirror image, much like left and right hands. A chiral molecule typically has at least one carbon atom bonded to four different substituents, leading to two distinct enantiomers. In contrast, achiral molecules can be superimposed on their mirror images and often possess a plane of symmetry.

Coordination Complexes

Coordination complexes consist of a central metal atom or ion bonded to surrounding molecules or ions called ligands. The arrangement and type of ligands can significantly influence the properties of the complex, including its chirality. In the case of the given reaction, the coordination environment around the cobalt ion changes, which can affect whether the resulting complex is chiral or achiral.

Substitution Reactions in Coordination Chemistry

Substitution reactions in coordination chemistry involve the replacement of one ligand in a complex with another. These reactions can lead to changes in the geometry and electronic properties of the complex. The specific nature of the ligands and their arrangement can determine the chirality of the product, as seen in the transformation of the cobalt complex in the question.