Chapter 9, Problem 9C.3BST

(a)

Interpretation Introduction

Interpretation:

The type of isomer represented by the pair $\left[\text{Co}{\left(\underset{\_}{\text{N}}\text{CS}\right)}_{\text{4}}{\left({\text{NH}}_{\text{3}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}$ and $\left[\text{Co}{\left(\text{NC}\underset{\_}{\text{S}}\right)}_{\text{4}}{\left({\text{NH}}_{\text{3}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}$ has to be given.

Concept Introduction:

Isomers:

The compounds with same molecular formula but differ in the arrangement of the atom are said to be isomers.

Linkage isomers:

Linkage isomerism occurs with ambidentate ligands that are capable of coordinating in more than one way.

Example:

${\text{SCN}}^{\text{-}}{\text{/NCS}}^{\text{-}}$.  The only difference is the atoms bind to the central ion.  The ligand must have more than one donor atom but bind to ion in only one place.

Answer to Problem 9C.3BST

The type of isomer represented by the pair $\left[\text{Co}{\left(\underset{\_}{\text{N}}\text{CS}\right)}_{\text{4}}{\left({\text{NH}}_{\text{3}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}$ and $\left[\text{Co}{\left(\text{NC}\underset{\_}{\text{S}}\right)}_{\text{4}}{\left({\text{NH}}_{\text{3}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}$ is linkage isomerism.

Explanation of Solution

In the isomer, $\left[\text{Co}{\left(\underset{\_}{\text{N}}\text{CS}\right)}_{\text{4}}{\left({\text{NH}}_{\text{3}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}$ the $\text{NCS}$ ligand is bound to the metal atom through the nitrogen atom while in another complex $\left[\text{Co}{\left(\text{NC}\underset{\_}{\text{S}}\right)}_{\text{4}}{\left({\text{NH}}_{\text{3}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}$ the ligand is bound to the metal through the sulphur atom.

The type of isomer represented by the pair $\left[\text{Co}{\left(\underset{\_}{\text{N}}\text{CS}\right)}_{\text{4}}{\left({\text{NH}}_{\text{3}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}$ and $\left[\text{Co}{\left(\text{NC}\underset{\_}{\text{S}}\right)}_{\text{4}}{\left({\text{NH}}_{\text{3}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}$ is linkage isomerism.

(b)

Interpretation Introduction

Interpretation:

The type of isomer represented by the pair $\left[\text{Cr}\text{Cl}{\left({\text{OH}}_{\text{2}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}{\text{.H}}_{\text{2}}\text{O}$ and $\left[\text{Cr}{\text{Cl}}_{\text{2}}{\left({\text{OH}}_{\text{2}}\right)}_{\text{4}}\right]\text{Cl}{\text{.2H}}_{\text{2}}\text{O}$ has to be given

Concept Introduction:

Hydrate Isomers:

Hydrate isomers results from replacement of a coordinated group by a solvent molecule in this case it is a water molecule.

Answer to Problem 9C.3BST

The type of isomer represented by the pair $\left[\text{Cr}\text{Cl}{\left({\text{OH}}_{\text{2}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}{\text{.H}}_{\text{2}}\text{O}$ and $\left[\text{Cr}{\text{Cl}}_{\text{2}}{\left({\text{OH}}_{\text{2}}\right)}_{\text{4}}\right]\text{Cl}{\text{.2H}}_{\text{2}}\text{O}$ is hydrate isomer.

Explanation of Solution

The given pair is $\left[\text{Cr}\text{Cl}{\left({\text{OH}}_{\text{2}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}{\text{.H}}_{\text{2}}\text{O}$ and $\left[\text{Cr}{\text{Cl}}_{\text{2}}{\left({\text{OH}}_{\text{2}}\right)}_{\text{4}}\right]\text{Cl}{\text{.2H}}_{\text{2}}\text{O}\text{.}$  In this pair of isomers the aqua ion which is bound with central atom is exchanged its place with the chloride ligand which present outside the nucleus.  Thus these isomers are hydrate isomers.

The type of isomer represented by the pair $\left[\text{Cr}\text{Cl}{\left({\text{OH}}_{\text{2}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}{\text{.H}}_{\text{2}}\text{O}$ and $\left[\text{Cr}{\text{Cl}}_{\text{2}}{\left({\text{OH}}_{\text{2}}\right)}_{\text{4}}\right]\text{Cl}{\text{.2H}}_{\text{2}}\text{O}$ is hydrate isomer.