Indicate the coordination number and the oxidation number of...

Indicate the coordination number and the oxidation number of the metal for each of the following complexes: (a) $\mathrm{Na}_{2}\left[\mathrm{CdCl}_{4}\right]$ (b) $\mathrm{K}_{2}\left[\mathrm{MoOCl}_{4}\right]$ (c) $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{2}\right] \mathrm{Cl}$ (d) $\left[\mathrm{Ni}(\mathrm{CN})_{5}\right]^{3-}$ (e) $\mathrm{K}_{3}\left[\mathrm{V}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]$ (f) $\left[\mathrm{Zn}(\mathrm{en})_{2}\right] \mathrm{Br}_{2}$

Indicate the coordination number and the oxidation number of the metal for each of the following complexes:
(a) $\mathrm{Na}_{2}\left[\mathrm{CdCl}_{4}\right]$
(b) $\mathrm{K}_{2}\left[\mathrm{MoOCl}_{4}\right]$
(c) $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{2}\right] \mathrm{Cl}$
(d) $\left[\mathrm{Ni}(\mathrm{CN})_{5}\right]^{3-}$
(e) $\mathrm{K}_{3}\left[\mathrm{V}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]$
(f) $\left[\mathrm{Zn}(\mathrm{en})_{2}\right] \mathrm{Br}_{2}$

Key Concepts

Coordination Number

The coordination number refers to the number of donor atoms directly bonded to the central metal ion in a coordination complex. It is determined by counting the points of attachment from the ligands and is a key factor in shaping the geometry and the overall structure of the complex.

Oxidation Number

The oxidation number is a formalism used to represent the charge on the central metal ion when all bonding is considered as purely ionic. It helps in understanding electron distribution within the complex, guiding predictions about reactivity and properties.

Ligands

Ligands are atoms, ions, or molecules that donate electron pairs to the central metal ion to form coordinate covalent bonds. Their ability to bind through one or multiple donor sites (monodentate or polydentate) influences both the coordination number and the geometry of the complex.

Coordination Complex

A coordination complex is an assembly comprising a central metal ion bonded to surrounding ligands. The structure, bonding, and reactivity of these complexes depend significantly on factors like the coordination number, the oxidation state of the metal, and the nature of the ligands involved.

Counter Ions

Counter ions are the spectator ions outside the coordination sphere that balance the overall charge of the complex. While they do not directly participate in the metal-ligand coordination, they are crucial for maintaining electrical neutrality of the compound.

Transcript

00:02 This question asks us to determine the coordination number and oxidation number for the metals in each complex.

00:10 So we're going to start with the first one, which is a.

00:14 So we have an a2 cd -cl4.

00:18 Now, the coordination number is the number of ligands attached to the metal within the complex.

00:26 So for this compound, the oxidation number, or i'm sorry, the coordination number, which is four, because we have four chlorines attached to this metal.

00:47 Now the oxidation number is going to be the charge of this metal in this entire complex.

00:55 So in order to do that, we need to calculate the charge of each component in the complex, where we know that cl4 is going to have an overall charge of minus i'm just going to write that above so we can keep track of it minus four.

01:12 Because chlorine overall is a minus one and there are four of them.

01:17 Sodium is going to have a plus two.

01:19 Sodium in eightly has a plus one and there's two of them.

01:23 That's plus two.

01:25 And then by that we know because this whole molecule is neutral, they didn't give us any charge at the end, that this metal needs to be a plus two.

01:37 Because it will need that plus two to balance out this whole chart.

01:46 So we have our station plus two.

01:52 We can do that for each of the complexes, where we have this k2 m -o -o -c -l.

02:00 Our coordination number is going to be five, because we have, oh, sorry, i wrote this wrong, this is co4.

02:10 We have five things attached to this molecule.

02:14 Our oxidation number, again, i'm going to write above with the charges of each molecule.

02:20 We'll start.

02:21 Over here, our potassium is a plus one charge.

02:24 There's two of them, so that's a plus two.

02:27 Our oxygen is going to have a minus two.

02:31 And then chlorine, again, has a minus one charge.

02:35 There's four of them.