Chapter 19, Problem 21QAP

Interpretation Introduction

(a)

Interpretation:

The name of the complex $\left[\text{Co}{\left(\text{en}\right)}_{\text{2}}\left(\text{SCN}\right){\text{Cl}}^{+}\right]$ needs to be determined.

Concept introduction:

Coordination compounds are those in which a transition metal atom is bonded to a ligand which can be neutral cation or anion. The transition metal element is enclosed within a bracket and a charge is present on the ion to balance the charge present on the ligands. The total charge present on any complex ion is equal to the sum of the oxidation number of the central metal atom and the total charge on the ligand present in it.

Answer to Problem 21QAP

The name of the compound will be chlorobis(ethylenediamine) thiocyanatocobalt(III).

Explanation of Solution

A ligand is an atom or a group of atoms or an anion having an unshared pair of electrons and thus it can act as a Lewis base. It can donate its pair of electrons to the metal atom to form a coordinate bond with the transition metal atom. The formula of the given complex is

$\left[\text{Co}{\left(\text{en}\right)}_{\text{2}}\left(\text{SCN}\right){\text{Cl}}^{+}\right]$

The total charge on complex cationis +1.Let ‘x’ be the oxidation state of ‘Co’ in the complex cation.

The oxidation state can be calculated as follows:

$\begin{array}{l}+1=x+2\left(0\right)+1\left(-1\right)+1\left(-1\right)\hfill \\ +1=x-2\hfill \\ x=+3\hfill \end{array}$

The oxidation state is written in the ROMAN number after the symbol of metal.

It consists of two ethylenediamine ligands which is a neutral ligand and is denoted by ‘en’ and number two is denoted by prefix ‘bis’ since the name of the ligand is itself very complex. Naming of the ligands in a given coordination compound takes place in an alphabetical order. SCN is an anionicmonodentate ligand and is named as ‘thiocyanato’ while naming in coordination compounds. Since chloride is an anionic ligand therefore is will be named as ‘chloro’.

The naming of the cation is done as such, therefore the name of the compound will be chlorobis(ethylenediamine)thiocyanatocobalt(III).

Interpretation Introduction

(b)

Interpretation:

The name of the complex $\left[\text{Ni}{\left(\text{CN}\right)}_{\text{4}}{}^{\text{2}-}\right]$ needs to be determined.

Concept introduction:

Coordination compounds are those in which a transition metal atom is bonded to a ligand which can be neutral cation or anion. The transition metal element is enclosed within a bracket and a charge is present on the ion to balance the charge present on the ligands. The total charge present on any complex ion is equal to the sum of the oxidation number of the central metal atom and the total charge on the ligand present in it.

Answer to Problem 21QAP

The name of this complex anion is tetracyanonickelate(II).

Explanation of Solution

A ligand is an atom or a group of atoms or an anion having an unshared pair of electrons and thus it can act as a Lewis base. It can donate its pair of electrons to the metal atom to form a coordinate bond with the transition metal atom. The formula of the given complex is

$\left[\text{Ni}{\left(\text{CN}\right)}_{\text{4}}{}^{\text{2}-}\right]$

For naming this compound, we can see that it consists of two cyanide ligands. It is an anionic ligand as it carries a charge of -1 and the number of such anionic ligands is denoted by adding prefix such as -di, -tri depending upon the number of the ligands. For naming complex ions, the oxidation state of the central metal atom is written at the end of the name in roman numerals in round brackets. Since the given compound is a complex anion, therefore, while naming the central metal atom, a suffix -ate is added to the name of the central metal atom. The total charge on the complex anion is -2. Let ‘ x’ be the oxidation state of ‘Ni’.

It can be calculated as follows:

$\begin{array}{l}-2=x+4\left(-1\right)\hfill \\ -2=x-4\hfill \\ x=-2+4\hfill \\ x=+2\hfill \end{array}$

Thus, the name of the complex will be tetracyanonickelate(II).

Interpretation Introduction

(c)

Interpretation:

The name of the complex $\left[\text{Zn}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_2^{3-}\right]$ needs to be determined.

Concept introduction:

Coordination compounds are those in which a transition metal atom is bonded to a ligand which can be neutral cation or anion. The transition metal element is enclosed within a bracket and a charge is present on the ion to balance the charge present on the ligands. The total charge present on any complex ion is equal to the sum of the oxidation number of the central metal atom and the total charge on the ligand present in it.

Answer to Problem 21QAP

The name of the compound is dioxalatozincate (II).

Explanation of Solution

A ligand is an atom or a group of atoms or an anion having an unshared pair of electrons and thus it can act as a Lewis base. It can donate its pair of electrons to the metal atom to form a coordinate bond with the transition metal atom. The formula of the given complex is as follows:

$\left[\text{Zn}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_2^{3-}\right]$

For naming this compound, one can see that it consists of two oxalate ligands. It is an anionic ligand as it carries a charge of -2 and the number of such anionic ligands is denoted by adding prefix such as -di, -tri depending upon the number of the ligands. For naming complex ions, the oxidation state of the central metal atom is written at the end of the name in roman numerals in round brackets. Since the given compound is a complex anion therefore while naming the central metal atom, a suffix -ate is added to the name of the central metal atom. The total charge on the complex cation is -2. Let ‘x’ be the oxidation state of ‘Zn’.

The oxidation state can be calculated as follows:

$\begin{array}{l}-2=x+2\left(-2\right)\hfill \\ -2=x-4\hfill \\ x=-2+4\hfill \\ x=+2\hfill \end{array}$

Thus, the name of the complex is dioxalatozincate(II).

Interpretation Introduction

(d)

Interpretation:

The name of the complex $\left[\text{Ag}\left({\text{NH}}_{\text{3}}\right)\text{Cl}\right]$ needs to be determined.

Concept introduction:

Coordination compounds are those in which a transition metal atom is bonded toa ligand which can be neutral, cation or anion. The transition metal element is enclosed within a bracket and a charge is present on the ion to balance the charge present on the ligands. The total charge present on any complex ion is equal to the sum of the oxidation number of the central metal atom and the total charges of the ligand present in it.

Answer to Problem 21QAP

The name of the coordination compound will be amminechlorosilver(I).

Explanation of Solution

A ligand is an atom or a group of atoms or an anion having an unshared pair of electrons and thus it can act as a Lewis base. It can donate its pair of electrons to the metal atom to form a coordinate bond with the transition metal atom. The formula of the given complex is as follows:

$\left[\text{Ag}\left({\text{NH}}_{\text{3}}\right)\text{Cl}\right]$

For naming this compound, one can see that it consists of one ammonia molecule. Ammonia is a neutral ligand and is denoted by ammine.The compound also consists of chlorine atom. Naming of the ligands in a given coordination compound takes place in an alphabetical order. When an anionic ligand is named a suffix -o is added at the end of the name of the ligand.Since chloride ion is an anionic ligand, therefore it will be named as ‘chloro’ in a coordination compound. For naming coordination compound, the oxidation state of the central metal atom is written at the end of the name in roman numerals in round brackets. The total charge on this coordination compound is zero. Let ‘x’ be the oxidation state of ‘Ag’

Thus,

$\begin{array}{l}0=x+1\left(0\right)+1\left(-1\right)\hfill \\ 0=x-1\hfill \\ x=+1\hfill \end{array}$

Therefore, the name of this compound will be amminechlorosilver(I).