Identify the type of structural isomerism that exists in each of the following pairs of compounds.
(a) [CoCl2(NH3)4]Cl·H2O and [CoCl(NH3)4(H2O)]Cl2
coordination isomerism
geometrical isomerism
hydrate isomerism
ionization isomerism
linkage isomerism
optical isomerism
(b) [Pt(NH3)4][PtCl6] and [PtCl2(NH3)4][PtCl4]
coordination isomerism
geometrical isomerism
hydrate isomerism
ionization isomerism
linkage isomerism
optical isomerism
I didn't draw (a) out but isn't that just hydrate isomerism; i.e., H2O is outside the coordination sphere in the first and inside in the second. It has switched with one Cl. AgNO3 would ppt 1 mol AgCl per mol complex for #1 but 2 mol AgCl per mol complex for #2.
(a) In the pair of compounds [CoCl2(NH3)4]Cl·H2O and [CoCl(NH3)4(H2O)]Cl2, the type of structural isomerism that exists is coordination isomerism. This is because the ligands (Cl and H2O) are exchanged between the metal center (Co) and the counterion (Cl-).
(b) In the pair of compounds [Pt(NH3)4][PtCl6] and [PtCl2(NH3)4][PtCl4], the type of structural isomerism that exists is linkage isomerism. This is because the ligands (Cl and NH3) are attached to different atoms, resulting in different overall structures of the complexes.
To identify the type of structural isomerism that exists in each pair of compounds, we need to understand the different types of isomerism.
(a) [CoCl2(NH3)4]Cl·H2O and [CoCl(NH3)4(H2O)]Cl2:
1. Coordination isomerism: This type of isomerism occurs when there is a difference in the coordination arrangement around the central metal ion. In this case, we see a difference in the positioning of the chloride ion and the water molecule within the coordination sphere of the cobalt ion. Therefore, this pair exhibits coordination isomerism.
2. Geometrical isomerism: Geometrical isomerism occurs when there is restricted rotation around a bond due to the presence of a double bond or a ring structure. However, this pair does not contain any double bonds or ring structures, so geometrical isomerism is not observed.
3. Hydrate isomerism: Hydrate isomerism occurs when compounds have the same chemical formula but a different number of water molecules associated with them. In this case, there is only one water molecule associated with each compound, so hydrate isomerism is not observed.
4. Ionization isomerism: Ionization isomerism refers to the isomers that differ in the way the ligands or groups are bonded to the central metal ion. Since this pair has the same ligands bonded to the central cobalt ion, but they differ in the positioning of the chloride ions, ionization isomerism is observed.
5. Linkage isomerism: Linkage isomerism occurs when ligands can bond to the central metal ion through different atoms. In this case, the ligands are bonded through the same atoms (chloride and ammonia), so linkage isomerism is not observed.
6. Optical isomerism: Optical isomerism occurs when compounds have a non-superimposable mirror image due to the presence of chiral centers. Neither of the compounds in this pair has a chiral center, so optical isomerism is not observed.
Therefore, the type of structural isomerism observed in this pair is coordination isomerism and ionization isomerism.
(b) [Pt(NH3)4][PtCl6] and [PtCl2(NH3)4][PtCl4]:
1. Coordination isomerism: Coordination isomerism occurs when there is a difference in the coordination arrangement around the central metal ion. In this pair, there is a difference in the placement of the chloride ion and the ammine ligands around the platinum ion. Therefore, this pair exhibits coordination isomerism.
2. Geometrical isomerism: Geometrical isomerism occurs when there is restricted rotation around a bond due to the presence of a double bond or a ring structure. However, this pair does not contain any double bonds or ring structures, so geometrical isomerism is not observed.
3. Hydrate isomerism: Hydrate isomerism occurs when compounds have the same chemical formula but a different number of water molecules associated with them. There are no water molecules associated with either compound in this pair, so hydrate isomerism is not observed.
4. Ionization isomerism: Ionization isomerism refers to the isomers that differ in the way the ligands or groups are bonded to the central metal ion. In this case, both compounds have the same ligands bonded to the central platinum ions, so ionization isomerism is not observed.
5. Linkage isomerism: Linkage isomerism occurs when ligands can bond to the central metal ion through different atoms. In this pair, both compounds have the same ligands bonded to the central platinum ions through the same atoms (chloride and ammonia), so linkage isomerism is not observed.
6. Optical isomerism: Optical isomerism occurs when compounds have a non-superimposable mirror image due to the presence of chiral centers. Neither of the compounds in this pair has a chiral center, so optical isomerism is not observed.
Therefore, the type of structural isomerism observed in this pair is coordination isomerism.