24.3 Stereoisomerism in Complex Ions

Question 1

What is a stereoisomer?

Answer 1

molecules with:

same structural formula

different arrangement of atoms in space

Question 2

What types of stereoisomerism can complex ions show?

Answer 2

1. cis-trans
2. optical (cis isomers only)

Question 3

What type of stereoisomer is this square planar complex ion? Draw the other isomer.

Answer 3

cis (same groups are on same sides)

Question 4

What type of stereoisomer is this octahedral complex ion? Draw the other isomer.

Answer 4

cis

Question 5

What type of stereoisomer is this octahedral complex ion? Draw the other isomer.

Answer 5

trans

Question 6

What type of stereoisomer is this square planar complex ion? Draw the other isomer.

Answer 6

trans (same groups are 180° from each other, opposite sides)

Question 7

What type of stereoisomer is this octahedral complex ion? Draw the other isomer.

Answer 7

cis (same groups 180° from each other)

Question 8

What type of stereoisomer is this octahedral complex ion? Draw the other isomer.

Answer 8

trans (same groups are 180° from each other)

Question 9

What causes cis-trans isomerism?

Answer 9

rigidity

which prevents groups from swapping places.

(rigidity usually arises due to a double bond, but in complex ions, groups are kept in position without)

Question 10

What is an optical isomer?

Answer 10

type of stereoisomerism

where molecules are non-superimposable mirror images of each other.

Question 11

What do octahedral complex ions require to show optical isomerism?

Answer 11

must be cis isomer

with 2 or more bidentate ligands

Question 12

Why can trans isomers not form optical isomers?

Answer 12

positioning of same groups opposite each other

means mirror images are exactly the same

& superimposable

Question 13

How can complex ions be used in medicine?

Answer 13

Cis-platin used to inhibit tumour growth

due to formation of platinum complex inside cells

which binds to DNA, preventing replication.

However, has many side effects