Q134 / 200 · MHT CET - Medical 2026 (25 April Shift 2) · Chemistry
Which of the following coordinate complexes contains one or more neutral ligand / ligands in its coordination sphere?
- APotassium trioxalatoaiuminate(III)
- Correct answerBPentaammineaquacobalt(III) iodide
- CSodium hexanitrocobaltate(III)
- DHexacyanoferrate(II) ion
Solution
Let us analyze the ligands present in the coordination sphere of each complex:
Potassium trioxalatoaluminate(III): $K_3[Al(C_2O_4)_3]$ contains oxalato ligands ($C_2O_4^{2-}$), which are anionic.
Pentaammineaquacobalt(III) iodide: $[Co(NH_3)_5(H_2O)]I_3$ contains ammine ($NH_3$) and aqua ($H_2O$) ligands, both of which are neutral molecules.
Sodium hexanitrocobaltate(III): $Na_3[Co(NO_2)_6]$ contains nitro ligands ($NO_2^{-}$), which are anionic.
Hexacyanoferrate(II) ion: $[Fe(CN)_6]^{4-}$ contains cyano ligands ($CN^{-}$), which are anionic.
Thus, pentaammineaquacobalt(III) iodide is the only complex containing neutral ligands in its coordination sphere.
Answer: Pentaammineaquacobalt(III) iodide
Potassium trioxalatoaluminate(III): $K_3[Al(C_2O_4)_3]$ contains oxalato ligands ($C_2O_4^{2-}$), which are anionic.
Pentaammineaquacobalt(III) iodide: $[Co(NH_3)_5(H_2O)]I_3$ contains ammine ($NH_3$) and aqua ($H_2O$) ligands, both of which are neutral molecules.
Sodium hexanitrocobaltate(III): $Na_3[Co(NO_2)_6]$ contains nitro ligands ($NO_2^{-}$), which are anionic.
Hexacyanoferrate(II) ion: $[Fe(CN)_6]^{4-}$ contains cyano ligands ($CN^{-}$), which are anionic.
Thus, pentaammineaquacobalt(III) iodide is the only complex containing neutral ligands in its coordination sphere.
Answer: Pentaammineaquacobalt(III) iodide
Hence, the correct answer is option: 'B'.