AIIMS 2018 Chemistry Complex Formation MCQ Question

The blue compound that crystallises when an aqueous solution of copper(II) sulfate is saturated with ammonia is [Cu(NH₃)₄]SO₄·H₂O, which features a square planar geometry around the copper ion due to the coordination of four ammonia ligands. Option B is incorrect because [Cu(NH₃)₄]SO₄ lacks water of crystallization and does not exhibit tetrahedral geometry; option C, [Cu(NH₃)₆]SO₄, suggests an octahedral complex that is not formed under these conditions; and option D, [Cu(SO₄)(NH₃)₅], incorrectly implies five ammonia ligands, which is not the stable configuration for copper(II) complexes in this scenario. Understanding the coordination chemistry of copper(II) and its complexes with ammonia is essential for predicting the structure and properties of these compounds.