What Factors Affect the Polarizability of Ligands?

[KarolinaPL]

Hi,
why polarizability of ligand -OH2 is bigger than of -H? what is the polarizability of NO2 comparing to them and e.g. I? i know that for halogens, it increase with increase of size of halogen down the group (electrons have more space on bigger atom), but how it is with other ligands?
Thank you.

 

[wilsont23274]

The polarizability of -OH2 is larger than -H because the oxygen atom in -OH2 has more electrons than the hydrogen atom in -H. This means that the electron cloud around the oxygen atom is larger and can be more easily distorted when exposed to an external electric field. The polarizability of NO2 is higher than both -OH2 and -H because the nitrogen atom has even more electrons than oxygen, so it will be even more easily distorted when exposed to an electric field. The polarizability of iodine (I) is even higher than NO2 since iodine has more electrons than nitrogen. This trend of increasing polarizability down a group holds true for many other ligands as well.