Find the number of strong field ligands from the following-N{{H}_{3}}, en, C{{l}^{-}}, C{{H}_{3}}CO{{O}^{-}}, C{{N}^{-}}

In coordination chemistry, strong-field ligands are those that form strong bonds with metal ions, leading to a high degree of splitting in the d-orbitals of the metal ion in a coordination complex. This strong splitting often results in low-spin complexes.

To determine whether a ligand is a strong-field ligand, you can use the spectrochemical series, which ranks ligands based on their ability to cause splitting of the d-orbitals. In general, ligands with a high charge density and multiple lone pair electrons are strong-field ligands.

Here's how the ligands you provided rank in terms of their strength as field ligands:

NH3 (Ammonia): Ammonia is a weak to moderate field ligand. It has a lone pair of electrons and can coordinate to metal ions, but it doesn't cause very strong splitting of the d-orbitals.

en (Ethylenediamine): Ethylenediamine is a strong-field ligand. It has two nitrogen atoms with lone pairs and can form strong bonds with metal ions, leading to significant d-orbital splitting.

Cl- (Chloride ion): Chloride ion is a weak field ligand. It has a single negative charge and does not have a significant effect on d-orbital splitting.

CH3COO- (Acetate ion): Acetate ion is a weak field ligand. While it has oxygen atoms with lone pairs, the negative charge is delocalized, and it doesn't cause strong splitting of d-orbitals.

CN- (Cyanide ion): Cyanide ion is a strong-field ligand. It has a high charge density and a lone pair of electrons on the nitrogen atom, making it a strong ligand that causes significant d-orbital splitting.

So, from the list you provided, en and CN- are strong-field ligands, while NH3, Cl-, and CH3COO- are weak field ligands.