Q1(b). Labile and inert complexes

Answer in brief

Labile complexes undergo rapid ligand substitution; inert complexes substitute slowly under the stated conditions. These are kinetic terms.

Key points

• Labile: ligand exchange is fast on the experimental time scale; aqua complexes such as [Cu(H₂O)₆]²⁺ and [Ni(H₂O)₆]²⁺ are familiar examples.
• Inert: ligand replacement has a substantial activation barrier and is slow; examples include [Co(NH₃)₆]³⁺ and [Cr(H₂O)₆]³⁺.
• Lability depends on the metal, oxidation state, electronic configuration, ligand and reaction conditions.
• Do not equate inert with thermodynamically stable: an unfavourable-to-form complex may persist because it reacts slowly.