Chemistry - Coordination Chemistry Question with Solution | TestHub
For the complex . Which of the following option is correct?
Options:
Answer:
Solution:
The complex is H[Co(CO)₄].
A. Oxidation state of Cobalt: H is +1, CO is neutral. So, +1 + x + 4(0) = 0, which means x = -1. Thus, Co is in the -1 oxidation state. Option A is incorrect.
B. Effective Atomic Number (EAN) rule: For Co(-1), atomic number is 27.
EAN = Atomic number - Oxidation state + 2 * (Number of ligands * Denticity)
EAN = 27 - (-1) + 2 * (4 * 1) = 28 + 8 = 36.
Since 36 is the atomic number of Krypton (a noble gas), the complex follows the EAN rule. Option B is correct.
C. Coordination number of Co: There are 4 CO ligands, each acting as a monodentate ligand. So, the coordination number is 4. Option C is incorrect.
D. Acidity/Basicity: H[Co(CO)₄] is a strong acid, similar to HCl. It acts as a Bronsted acid, not a base. Option D is incorrect.
Therefore, the correct option is B.