Stereoisomerism in complex ions 210-211

Question 1

Define the term stereoisomers.

Answer 1

Stereoisomers are species with the same structural formula but with a different arrangement of atoms in space.

Question 2

What are the type of stereoisomerism in transition element chemistry?

Answer 2

• cis-trans isomerism.
• optical isomers.

Question 3

Draw the cis and trans isomers of [Co(NH₃)Cl₂]⁺.

Answer 3

Cis: - The two Cl- ligands are at adjacent corners of the octahedron. The two Cl^- ligands are at 90* to one another.

Trans: - The two Cl^- ligands are at opposite corners of the octahedron.-The two Cl- ligands are 180* to one another.

Question 4

Draw the cis and trans isomers of the complex ion [NiCl₂(NH₃)₂].

Answer 4

• This shape is rather like an octahedral complex, but without the ligands above and below the plane.

For cis-trans isomerism, the complex must contain two different ligands, with two of one ligand and two of the other.

Question 5

Explain the structure of the compound cis-platin and explain its use.

Answer 5

Cis-platin is one of the most effective drugs against many forms of cancer. Cis-platin is the cis-isomer of a platinum complex, [PtCl₂(NH₃)₂].

• It is believed that cis-platin acts by binding the DNA of a fast-growing cancer cells. This alters the DNA in the cancerous cells. It is generally believed that the cells are prevented from reproducing by these changes to the DNA structure.