## order of ligand names [ENDORSED]

Emmy Son 4f
Posts: 8
Joined: Mon Jan 26, 2015 2:17 pm

### order of ligand names

How is the order of each ligand name determined? ex. [Co(Nh3)5Cl]Cl penta aminne chloro cobalt (2) Why do we start with naming the center first?

Roya_N
Posts: 8
Joined: Fri Jun 17, 2016 11:28 am

### Re: order of ligand names  [ENDORSED]

The ligands are named first in alphabetic order then the metal is named followed by the oxidation state.

Hope this helps in some way!

Sara Juarez 1B
Posts: 8
Joined: Tue Nov 24, 2015 3:00 am

### Re: order of ligand names

When working from name to the formula of a molecule, does the order matter? I know that if we are given the formula and then we are asked for the name we are require to write it in alphabetical order but how does it work if we are given the name first and we are trying to figure out the formula for the molecule?

Chem_Mod
Posts: 19157
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 828 times

### Re: order of ligand names

You do not need to write the formula in any order, but you do need to order the atoms of the ligand in a way that the atom of the ligand which coordinates to the metal is listed first. There is a big difference between (NC) and (CN) ligands.

HannahLewis
Posts: 10
Joined: Wed Nov 18, 2015 3:00 am

### Re: order of ligand names

What is the difference between (NC) and (CN) ligands then?

Kevin Tam 1J
Posts: 23
Joined: Wed Sep 21, 2016 2:59 pm

### Re: order of ligand names

The NC ligand suggests that the nitrogen (N) is bonded to the central cation. However, the CN ligand suggests that the carbon (C) is bonded to the central cation.

Sydney Wu 2M
Posts: 50
Joined: Fri Jul 22, 2016 3:00 am

### Re: order of ligand names

I notice that when water is a ligand (looking at #31), the SSM writes its formula as H2O for one exercise and OH2 for another one. I know the order of the atoms matter, so which one is correct? Why?

Kevin Tam 1J
Posts: 23
Joined: Wed Sep 21, 2016 2:59 pm

### Re: order of ligand names

I think that for H2O, it is already implied/understood that the oxygen (not the hydrogen) is bonded to the central cation, so writing it either way (as H2O or OH2) is fine, although I think it is better to write it as OH2. In other words, there is only one possible way for the water to bond to the central cation.

However, for something like CN, there are two possibilities: CN (cyano) and NC (isocyano). CN( cyano) implies that the carbon atom is bonded to the central ation whereas NC (isocyano) implies that the nitrogen is bonded to the central cation.