Chapter 22, Problem 22.19QP

Interpretation Introduction

Interpretation: The formulas for each of the given compounds are to be stated.

Concept introduction: The coordination complex consists of coordination sphere in which ligands are joined through covalent bond to the central metal ion. The oxidation state of central metal ion is satisfied by the presence of counter ions in ionization sphere.

To determine: The formulas for each of the given compounds.

Answer to Problem 22.19QP

Solution

The formulas for each of the given compounds are rightfully stated.

Explanation of Solution

Explanation

When octahedral platinum (IV) complexes react with ${\text{AgNO}}_{\text{3}}\left(aq\right)$ the compound with general formula $\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_x{\text{Cl}}_{\text{4}}$ is formed. The table showing the composition of complex and the number of moles of $\text{AgCl}$ produced per mole of complex is,

$\begin{array}{cc}\text{Composition}& \text{Number}\text{of}\text{moles}\text{of}\text{AgCl}\\ \text{of}\text{complex}& \text{produced}\text{per}\text{mole}\text{of}\\ & \text{complex}\text{added}\\ \text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_{\text{6}}{\text{Cl}}_{\text{4}}& \text{4}\\ \text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_{\text{5}}{\text{Cl}}_{\text{4}}& \text{3}\\ \text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_{\text{4}}{\text{Cl}}_{\text{4}}& \text{2}\\ \text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_{\text{3}}{\text{Cl}}_{\text{4}}& \text{1}\\ \text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_{\text{2}}{\text{Cl}}_{\text{4}}& \text{0}\end{array}$

The complex with composition $\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_6{\text{Cl}}_{\text{4}}$ is considered. It is an octahedral complex. The given complex produces $4$ moles of $\text{AgCl}$ on addition with ${\text{Ag}}^{\text{+}}$ which indicates that there is $4$ chloride ions present outside the coordination sphere of the complex. The reaction of the complex with the ${\text{Ag}}^{\text{+}}$ ions is,

$\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_6\right]{\text{Cl}}_{\text{4}}+4{\text{Ag}}^{\text{+}}\stackrel{}{\to }{\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_6\right]}^{4+}+4\text{AgCl}$

The coordination number in octahedral complex is satisfied by having six ${\text{NH}}_{\text{3}}$ in the coordination sphere. The oxidation state of $\text{Pt}\left(\text{IV}\right)$ is satisfied when all $4$ ${\text{Cl}}^{-}$ ions are in the ionization sphere. Hence, the formula of the complex is $\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_6\right]{\text{Cl}}_{\text{4}}$.

The complex with composition $\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_5{\text{Cl}}_{\text{4}}$ is considered. It is an octahedral complex. The given complex produces $3$ moles of $\text{AgCl}$ on addition with ${\text{Ag}}^{\text{+}}$ which indicates that there is $3$ chloride ions present outside the coordination sphere of the complex. The reaction of the complex with the ${\text{Ag}}^{\text{+}}$ ions is,

$\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_5\text{Cl}\right]{\text{Cl}}_3+3{\text{Ag}}^{\text{+}}\stackrel{}{\to }{\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_5\text{Cl}\right]}^{4+}+3\text{AgCl}$

The coordination number in octahedral complex is satisfied by having $5$ ${\text{NH}}_{\text{3}}$ and $1$ chlorine in the coordination sphere. The oxidation state of $\text{Pt}\left(\text{IV}\right)$ is satisfied when $3$ ${\text{Cl}}^{-}$ ions are in the ionization sphere and $1$ chlorine ligand is present in the coordination sphere. Hence, the formula of the complex is $\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_{\text{5}}\text{Cl}\right]{\text{Cl}}_3$.

The complex with composition $\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_4{\text{Cl}}_{\text{4}}$ is considered. It is an octahedral complex. The given complex produces $2$ moles of $\text{AgCl}$ on addition with ${\text{Ag}}^{\text{+}}$ which indicates that there is $2$ chloride ions present outside the coordination sphere of the complex. The reaction of the complex with the ${\text{Ag}}^{\text{+}}$ ions is,

$\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_4{\text{Cl}}_2\right]{\text{Cl}}_2+2{\text{Ag}}^{\text{+}}\stackrel{}{\to }{\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_4{\text{Cl}}_{\text{2}}\right]}^{4+}+2\text{AgCl}$

The coordination number in octahedral complex is satisfied by having $4$ ${\text{NH}}_{\text{3}}$ and $2$ chlorine in the coordination sphere. The oxidation state of $\text{Pt}\left(\text{IV}\right)$ is satisfied when $2$ ${\text{Cl}}^{-}$ ions are in the ionization sphere and $2$ chlorine ligands are present in the coordination sphere. Hence, the formula of the complex is $\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_4{\text{Cl}}_2\right]{\text{Cl}}_2$.

The complex with composition $\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_3{\text{Cl}}_{\text{4}}$ is considered. It is an octahedral complex. The given complex produces $1$ moles of $\text{AgCl}$ on addition with ${\text{Ag}}^{\text{+}}$ which indicates that there are $1$ chlorides ions present outside the coordination sphere of the complex. The reaction of the complex with the ${\text{Ag}}^{\text{+}}$ ions is,

$\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_3{\text{Cl}}_3\right]\text{Cl}+{\text{Ag}}^{\text{+}}\stackrel{}{\to }{\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_3{\text{Cl}}_3\right]}^{4+}+\text{AgCl}$

The coordination number in octahedral complex is satisfied by having $3$ ${\text{NH}}_{\text{3}}$ and $3$ chlorine in the coordination sphere. The oxidation state of $\text{Pt}\left(\text{IV}\right)$ is satisfied when $1$ ${\text{Cl}}^{-}$ ion is in the ionization sphere and $3$ chlorine ligands are present in the coordination sphere. Hence, the formula of the complex is $\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_3{\text{Cl}}_3\right]\text{Cl}$.

The complex with composition $\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_2{\text{Cl}}_{\text{4}}$ is considered. It is an octahedral complex. The given complex produces $0$ moles of $\text{AgCl}$ on addition with ${\text{Ag}}^{\text{+}}$ which indicates that there is no chloride ions present outside the coordination sphere of the complex. The reaction of the complex with the ${\text{Ag}}^{\text{+}}$ ions is,

$\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_2{\text{Cl}}_4\right]+{\text{Ag}}^{\text{+}}\stackrel{}{\to }{\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_2{\text{Cl}}_4\right]}^{4+}+{\text{Ag}}^{+}$

The coordination number in octahedral complex is satisfied by having $2$ ${\text{NH}}_{\text{3}}$ and $4$ chlorine in the coordination sphere. The oxidation state of $\text{Pt}\left(\text{IV}\right)$ is satisfied when $4$ chlorine ligands are present in the coordination sphere. Hence, the formula of the complex is $\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_2{\text{Cl}}_4\right]$.

Conclusion

The formulas for each of the given compounds are,

• $\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_6\right]{\text{Cl}}_{\text{4}}$.
• $\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_{\text{5}}\text{Cl}\right]{\text{Cl}}_3$.
• $\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_4{\text{Cl}}_2\right]{\text{Cl}}_2$.
• $\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_3{\text{Cl}}_3\right]\text{Cl}$.
• $\left[\text{Pt}{\left({\text{NH}}_{\text{3}}\right)}_2{\text{Cl}}_4\right]$