Question

Which from following coordinate complexes contains neutral ligand ?

• A. Pentacarbonyliron (0)
• B. Hexacyanoferrate (II) ion
• C. Trioxalatocobaltate (III) ion
• D. Sodium hexanitrocobaltate (III)

Hint:

Look for ligands such as CO, NH3 or H2O that carry no charge.

Answer 1

The Correct Option is A

Step 1: Decode the names
"carbonyl" = CO, "cyano" = $\text{CN}^-$, "oxalato" = $\text{C}_2\text{O}_4^{2-}$, "nitro" = $\text{NO}_2^-$.

Step 2: Charges
CO is neutral. The other three ligands have negative charges.

Step 3: Check with oxidation number
Pentacarbonyliron(0) has Fe in oxidation state 0 because all five CO ligands carry no charge, in agreement with the "(0)" in the name.

Step 4: Answer
Option (A).

Final Answer:
Only pentacarbonyliron(0) has a neutral ligand. This is option (A). \[ \boxed{\text{(A) }\text{Pentacarbonyliron(0)}} \]