Question

Define the coordination number and oxidation state of the central metal ion in \([Co(NH_3)_6]Cl_3\).

• A. Coordination number = 4, Oxidation state = +2
• B. Coordination number = 6, Oxidation state = +3
• C. Coordination number = 6, Oxidation state = +2
• D. Coordination number = 3, Oxidation state = +3

Hint:

Neutral ligands such as \(NH_3\), \(H_2O\), and \(CO\) contribute zero charge when calculating oxidation states in coordination compounds.

Answer 1

The Correct Option is B

Concept:
• Coordination number is the number of ligand donor atoms directly bonded to the central metal ion.
• Oxidation state of the central metal ion is calculated using the overall charge of the complex and the charges of the ligands.

Step 1: Determine the coordination number. In the complex ion: \[ [Co(NH_3)_6]^{3+} \] There are six \(NH_3\) ligands attached to the cobalt atom. Since each \(NH_3\) acts as a monodentate ligand, the coordination number is \[ \boxed{6} \]

Step 2: Determine the oxidation state of cobalt. Ammonia \((NH_3)\) is a neutral ligand, so it contributes 0 charge. Let the oxidation state of cobalt be \(x\). \[ x + 6(0) = +3 \] \[ x = +3 \] Thus, the oxidation state of cobalt is \[ \boxed{+3} \]