Increasing order of donating power of ligands

There are several ways to remember the increasing order of donating power of ligands, but one of the most popular tricks is using the acronym "SALC" which stands for:

S - Strong field ligands
A - Ambidentate ligands
L - Weak field ligands
C - Cyanide and Carbon monoxide

Let's break down each category in more detail:

Strong field ligands:
These ligands have a high donating power and form strong bonds with the central metal ion. They usually have a large size and a high charge density. Examples include:

- Cyanide (CN-)
- Carbon monoxide (CO)
- Nitrite (NO2-)
- Isocyanide (NC-)
- Thiocyanate (SCN-)

Ambidentate ligands:
These ligands have more than one atom that can donate electrons to the central metal ion. They usually form chelate complexes with the metal ion. Examples include:

- Ethylenediamine (en)
- Glycinate (gly)
- Oxalate (ox)
- 1,2-dithiolate (dmit)

Weak field ligands:
These ligands have a low donating power and form weak bonds with the central metal ion. They usually have a small size and a low charge density. Examples include:

- Water (H2O)
- Ammonia (NH3)
- Chloride (Cl-)
- Bromide (Br-)
- Iodide (I-)
- Fluoride (F-)

Cyanide and Carbon monoxide:
These two ligands form a special category because of their high donating power and toxicity. They can bind to the metal ion in multiple ways, forming different types of complexes.

Overall, the increasing order of donating power of ligands can be remembered as SALC, with strong field ligands having the highest donating power and weak field ligands having the lowest. However, it's important to note that this is just one way to classify ligands and their properties can vary depending on the specific metal ion and coordination environment.