Which one of the following is least likely to act as a ligand with Fe²⁺ ions? A - VCE - SSCE Chemistry - Question 20 - 2005 - Paper 1

To determine which ligand is least likely to act with Fe²⁺ ions, we can analyze the potential ligands:

1. F^-: Fluoride is a simple anion with a lone pair of electrons, making it a potential ligand.
2. CN^-: Cyanide is a strong field ligand due to its ability to form stable complexes, hence it is very likely a strong ligand for Fe²⁺.
3. H₂O: Water is a neutral ligand but is weaker compared to the others due to its smaller charge and less effective coordination capability.
4. NH₄⁺: Ammonium can act as a weak ligand though it’s positively charged.

Considering these factors, H₂O is the least likely to act as a ligand with Fe²⁺ ions due to its lower ligand strength compared to the others.