Ligands

[Amy Shimizu 1J]

Hi, could someone clarify what a ligand is and how to find them? Specifically, for the heme group, how do you know that all four N's are one ligand?

[Nika Kononov 3E]

A ligand is an ion or a molecule that is bonded to a metal atom. In the heme group the Nitrogen are not all one ligand. Since the Nitrogen are individually bonded to the Iron, they are separate ligands. The Nitrogens and Iron all make a single coordination compound.

[rachelcameron2E]

To add, if you are looking at the formula of a coordination compound, the elements/molecule/ions inside the brackets that are after the metal cation will be the ligands. For example, if you had a coordination compound like [Fe(NH3)3(CN)3], the ligands would be CN and NH3 as they come after Fe. For naming, the ligands come first in alphabetical order. For the example, the name would be triamminetricyanoiron(III). I hope this helps!