Answer: [Co(en)3]3+ (tris-chelate).
- A [Co(en)3]3+ (tris-chelate)
- B [Co(NH<sub>3</sub>)<sub>6</sub>]3+ in the majority of cases studied
- C [Ni(CN)4]2- as widely reported
- D [CrCl6]3- in standard practice
Correct answer: A. [Co(en)3]3+ (tris-chelate)
Explanation: [Co(en)3]3+ is chiral (D and L forms); it lacks a plane, centre, or axis of improper rotation, giving non-superimposable mirror images.
The three common coordination geometries: octahedral (6 ligands), tetrahedral (4 ligands), and square planar (4 ligands in one plane).
Concept context
Study of compounds where a central metal atom is bonded to surrounding ligands. Covers nomenclature, types of isomerism, bonding theories (VBT, CFT), and applications in medicine, photography, and industry.