Q29E - Chemistry (OpenStax)

Question

Sketch the structures of the following complexes. Indicate any cis, trans, and optical isomers.

\(\begin{aligned}{\underline{\phantom{xx}}}(a)\left( {Pt{{\left( {{H_2}O} \right)}_2}B{r_2}} \right)\\(b)\left( {Pt\left( {N{H_3}} \right)(py)(Cl)(Br)} \right)\\(c)\left( {Zn{{\left( {N{H_3}} \right)}_3}Cl} \right)\\(d){\left( {Pt{{\left( {N{H_3}} \right)}_3}Cl} \right)^ + }\\(e)\left( {Ni{{\left( {{H_2}O} \right)}_4}C{l_2}} \right)\\(f){\left( {Co{{\left( {{C_2}{O_4}} \right)}_2}C{l_2}} \right)^{3 - }}\end{aligned}\)

Step-by-Step Solution

Answer

Isomers are the chemical species which have the same molecular formula but with different arrangement of atoms or ligands in space. 

Explanation

(a)

• In \(\left( {Pt{{\left( {{H_2}O} \right)}_2}B{r_2}} \right)\), We can see that central metal atom \(Pt\) is attached to \(2\)molecules of \({{\rm{H}}_2}{\rm{O}}\)and \(2{\rm{B}}{{\rm{r}}^ - }\)ions in square planar arrangement. Like that it will have \(2\) isomers: cis and trans.

(b)

• In \(\left( {Pt\left( {N{H_3}} \right)(py)(Cl)(Br)} \right)\), We can see that central metal atom \(Pt\) is attached to \(4\) different groups in square planar arrangement .Like that, it will have \(3\) isomers:.

(c)

• In \(\left( {Zn{{\left( {N{H_3}} \right)}_3}Cl} \right)\), We can see that central metal atom \({\rm{Zn}}\)is attached to \(3\)ammonia molecules and \(1{\rm{C}}{{\rm{l}}^ - }\)ion in tetrahedral arrangement. This molecule does not have optical isomerism.

(d) In \({\left( {Pt{{\left( {N{H_3}} \right)}_3}Cl} \right)^ + }\), We can see that central metal atom \({\rm{Zn}}\)is attached to \(3\) ammonia molecules and \(1{\rm{C}}{{\rm{l}}^ - }\)ion in tetrahedral arrangement This molecule does not have optical isomerism.

(e)

• In \(\left( {Ni{{\left( {{H_2}O} \right)}_4}C{l_2}} \right)\), We can see that central metal atom \(Ni\) is attached to \(4\)molecules of \({{\rm{H}}_2}{\rm{O}}\)and \(2{\rm{C}}{{\rm{l}}^ - }\)ions in octahedral arrangement. Like that it will have \(2\) isomers: cis and trans.

(f)

• In\({\left( {Co{{\left( {{C_2}{O_4}} \right)}_2}C{l_2}} \right)^{3 - }}\), We can see that central metal atom \(Co\) is attached to \(2\) bidentate molecules \({{\rm{C}}_2}{\rm{O}}_4^{2 - }\)and \(2{\rm{C}}{{\rm{l}}^ - }\)ions. Like that it will have \(3\) isomers: \(2\)cis, which are also optical isomers, and trans. 
• Trans isomer will not show optical isomerism since it contains a plane of symmetry.

Result

1. It has \(2\) isomers. 

2. It has 3 isomers.

3. It has 0 isomers.

4. It has 0 isomers.

5. It has 2 isomers.

6. It has 3 isomers.