Homework 17.33

[Omer Lavian 2K]

17.33 Which of the following ligands can be polydentate? If
the ligand can be polydentate, give the maximum number of
places on the ligand that can bind simultaneously to a single
metal center: (a) HN(CH2CH2NH2)2; (b) CO3
2!; (c) H2O;
(d) oxalate.

What makes a ligand able to be polydentate? Additionally, how do you determine which atoms bond to the central metal?

[Sedra_Tibi_1L]

A polydentate is a ligand that bonds to more than one site simultaneously, for example, bidentate (2 different bonding regions). Coordination compounds are made up of ligands that bond to the central atom. The central atom is usually the metal or cation.

[Derek Lee 2K]

The way I've been doing it and how the solution manual shows you is to do a basic sketch of the structure and then you look at which atoms have lone pairs. Lone pairs means its free to bind to another atom so you count up the atoms with lone pairs and that corresponds to what type of polydentate it is.

for example: one lone pair on one oxygen atom = monodentate

[Amy Ko 3C]

The answer to this homework question is
a) HN(CH2CH2NH2)2, the 3 Nitrogen atoms have lone pairs to bond with a metal center atom, thus is polydentate
b) CO3^2- can bond with a metal atom with one or two Oxygen atoms
c) H2O is monodentate
d) C2O4^2- can bond with a metal atom with 2 Oxygen atoms

You can determine this by drawing a sketch of the molecule and see which atom has lone pairs, which usually indicate the location to bind with the metal atom

[Liam Giffin 2B]

For part a of 33 the lewis structure I got (pictured below) would suggest that it is a bidentate ligand. Why is that incorrect?

[Omer Lavian 2K]

Also the SO42- ligand has 4 atoms with lone pairs, but it isn't shaped in a way that would indicate that it is tetra dentate. My guess is that like carbonato, it can be mono or bidentate. Thoughts?

[Omer Lavian 2K]

Also the SO42- ligand has 4 atoms with lone pairs, but it isn't shaped in a way that would indicate that it is tetra dentate. My guess is that like carbonato, it can be mono or bidentate. Thoughts?

[Omer Lavian 2K]

Sorry for posting so much but Liam, I remember Dr. Lavelle drawing the molecule in class with an N-C-C-N structure. I assume that this gives all the N's a formal charge of zero, whereas you have one N with a -1 charge and another with a +1.

[arielle_cunanan3K]

Can someone explain how part b, CO3^2- can be both monodentate or bidentate?