Chemistry - Coordination Chemistry Question with Solution | TestHub

In [Co(en)₃]Cl₃, the complex cation is [Co(en)₃]³⁺, so its IUPAC name is tris(ethylenediamine)cobalt(III) chloride. The three Cl⁻ ions are outside the coordination sphere, hence 1 mol of the complex gives 3 mol AgCl with excess AgNO₃. Cobalt is Co³⁺ (3d⁶) and en is a strong-field ligand, giving a low-spin octahedral complex with $t_{2g}^6{e}_g^0$ configuration. Since CN⁻ is a stronger-field ligand than en, ${\Delta }_o$ for [Co(en)₃]³⁺ is lower than that of [Co(CN)₆]³⁻. Therefore, A, B, C and D are correct.