Indicate the coordination number and the oxidation number of the metal for each of the following

step 1 Alright, so here is the problem 23 .26. We're going to find the oxidation number and the coordin

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

Key Concepts

Polydentate (Chelating) Ligands

Polydentate or chelating ligands have multiple donor sites that can simultaneously bond to a central metal ion. This multidentate coordination increases the stability of the complex via the chelate effect, and it directly affects the coordination number by contributing more than one bonding interaction per ligand.

Coordination Number

The coordination number is the number of ligand donor atoms that are directly bonded to the central metal ion. Determining the coordination number involves counting each donor atom from the ligands, taking into account whether the ligand is monodentate (donates one pair of electrons) or polydentate (donates multiple pairs). This concept is fundamental in understanding the geometry and bonding in coordination compounds.

Oxidation Number

The oxidation number of the metal in a coordination complex represents its hypothetical charge if all ligands were removed along with the bonding electrons. It is calculated by balancing the known charges of the ligands and any counter ions with the overall charge of the complex. This concept is crucial for predicting reactivity and electronic structure in coordination chemistry.

Ligands

Ligands are ions or molecules that donate electron pairs to the central metal ion to form coordination bonds. They vary in the number of donor atoms they possess, influencing both the coordination number and the stability of the complex. Understanding ligand properties, such as charge and denticity, is essential in coordination chemistry.

Counter Ions and Overall Charge Balancing

Counter ions are ions that balance the overall charge of a coordination compound. They are not directly bonded to the central metal ion but are essential in maintaining electrical neutrality. Their presence influences the calculation of the metal’s oxidation state and helps in understanding the complete chemical formula of the complex.

Transcript

00:01 Alright, so here is the problem 23 .26.

00:03 We're going to find the oxidation number and the coordination number of the metal for each of the following complexes.

00:10 So first, we want to understand one of the concepts that tells us the primary valency will be ionic.

00:21 Or you can say it's ionizable, and that is correspond to the oxidation number of the central metal.

00:31 And the secondary valency is non -ionizable, and that corresponds to the coordination number of the central metal.

00:49 All right, so now let's look at the question a.

00:52 We have a complex k3, co, cn6.

01:00 So for this complex, we know the oxidation number for potassium is equal to positive 1.

01:07 And we know the cyanide has an oxidation number equal to negative 1.

01:12 So if we assume that the oxidation number for the metal cobalt equal to x, we have the following equation, that is 3 times 1 plus x plus 6 times negative 1 equal to the total or the net charge of the molecule, which is 0.

01:35 So to simplify this equation, we get 3 plus x minus 6 equal to 0.

01:43 And solving this equation, we get x equal to positive 3.

01:48 So this number positive 3 is the oxidation number of the metal cobal.

01:58 So then we look for the coordination number.

02:01 We see that the total number of ligands attached to the metal within the square bracket right here are 6.

02:09 Cyanide and this six cyanide is attached to the metal cobalt so the coordination number of this center atom cobalt is equal to six all right so that's complete for the part a we look for part b part b we have another complex n a 2 c d b r 4 so for this complex we know the oxidation number of sodium is equal to positive 1, and the oxidation number for bromine will be negative 1.

02:57 So once again, we assume the atom, metal, cadmium, have an oxidation number equal to x.

03:06 We got the following equation, 2 times 1 plus x, plus 4 times negative 1, equal to the total oxidation number of the complex, that is 0.

03:21 So to simplify this equation, we get 2 plus x minus 4 equal to 0.

03:29 All right, so we solve for the number, x we get x equal to positive 2.

03:35 So the number positive 2 is the oxidation number for the central metal cadmium.

03:44 All right, so now let's look at the coordination number.

03:47 So the total number of ligand attached to the metal within the square bracket is 4.

03:54 So 4 bromide is attached to the center metal cadmium.

04:03 So the coordination number of this metal will equal to 4.

04:14 That is the part b.

04:16 Now let's look at part c.

04:19 We have a complex p -t -e -n.

04:24 N3, clo4, 4.

04:32 So in this complex, we know the oxidation number of ethylene diamine, or it can say en, equal to 0.

04:42 And for the perchlorate, clo4, the oxidation number is negative 1.

04:49 So if we consider the oxidation number for platinum equal to x, we will have the equation x plus 3 times 0 plus 4 times negative 1 equal to the net charge 0.

05:06 So x minus 4 equal to 0.

05:10 We get the number x will be equal to positive 4.

05:15 So this positive 4 will be the oxidation number of the center metal platinum.

05:23 All right.

05:24 So now let's look at the coordination number here.

05:27 So the total number of ligand attached to the metal within the square bracket right here is three.

05:35 So three ethylene diamine is attached to the center atom.

05:43 However, this ethylene diamine is a biotentate ligand, which means it donates two pairs of electrons to the center metal...