JEE Main · 2021 · 27 Jul 2021 · Shift 2 · Coordination Compounds

3 moles of metal complex with formula

Co (en)_{2} Cl_{3}

, gives 3 moles of silver chloride on treatment with excess of silver nitrate. The secondary valency of Co in the complex is ____. (Round off to the Nearest Integer).

Answer: 6

Solution

Three moles of the complex give three moles of silver chloride, so one chloride per formula unit is free in solution and the other two stay bound to the metal; the complex is

[Co (en)_{2} C l_{2}] Cl

. Secondary valency is the number of donor atoms held directly by the central metal. Each ethylenediamine is bidentate and contributes two nitrogen donors, giving four, and the two coordinated chloride ions contribute two more. The secondary valency of cobalt in the complex is

6

JEE Main · 2021 · 27 Jul 2021 · Shift 2 · Integer answer

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