Lecture 2

Question 1

Meaning of isomer

Answer 1

Two or more different compounds having the same formula but different structures

Question 2

How do the different type of isomers branch out?

Answer 2

Isomer
|
Stereoisomer———————Structural isomer
|
Conformational———Configurational
|
Optical:—————Diastereoisomers
Enantiomers

Question 3

How is stereoisomers and structural split up?

Answer 3

𝐒𝐭𝐞𝐫𝐞𝐨𝐢𝐬𝐨𝐦𝐞𝐫𝐢𝐬𝐦 - different arrangement of atoms in space
G eometric
O ptical

𝐒𝐭𝐫𝐮𝐜𝐭𝐮𝐫𝐚𝐥 𝐢𝐬𝐨𝐦𝐞𝐫𝐢𝐬𝐦 - different bonds between atoms
C oordination
H yrdrate
I onisation
L inkage
L igand

Question 4

Importance of isomerism

Answer 4

Eg cis-platin treats cancer and trans-platin has no effect

How it works:
In blood plasma there is a high concentration of CL- so stays in its original form
Inside cell there is a lower Cl- concentration, causing the coordination of Pt to N atoms of nucleotide bases (Guanine preferred)
Binds to DNA, intrastrand crosslinks which chelates DNA
It is cytotoxic

Cis-[PtCl2(NH3)2] -> cis-[Pt(H20)2(NH3)2]2+

Question 5

Geometric isomers for CN=4

Where M - metal
a/𝐛- different monodentate ligands

Answer 5

Trans
a 𝐛
\ /
M
/ \
𝐛 a

Cis
𝐛 a
\ /
M
/ \
𝐛 a

Question 6

Geometric isomers for CN=4

Where M - metal
a/𝐛/c- different monodentate ligands

Answer 6

Trans
a 𝐛
\ /
M
/ \
𝐛 c

Cis
𝐛 a
\ /
M
/ \
𝐛 c

Question 7

Geometric isomers for CN=4

Where M - metal
a/b/c/d - different monodentate ligands

How many different options for isomers are there?

Answer 7

There are 3:

a trans to b
a trans to c
a trans to d

Question 8

Geometric isomers for CN=4

Where M - metal
a/c- different monodentate ligands
𝐛 - bidentate ligand

For Ma2𝐛2 and Ma𝐛2c

Answer 8

Ma2𝐛2:
______
/ \
𝐛 𝐛
\ /
M
/ \
a a

Ma𝐛2c
______
/ \ Note: if b—b is not symmetrical, there is one
𝐛 𝐛 more isomer of Ma𝐛2c where a and c are
\ / switched round
M
/ \
a c

Question 9

Geometric isomers for CN=4

Where M - metal
a/𝐛 - different monodentate ligands

For [Ma4𝐛2]

Answer 9

𝐛
a | a Trans
\ | /
M
/ | \
a | a
𝐛

    𝐛   a    |    a    Cis
 \  |  /
    M
 /  |  \   𝐛    |    a
    a

Question 10

Geometric isomers for CN=4

Where M - metal
a/𝐛 - different monodentate ligands

For [Ma3𝐛3]

Answer 10

a
a | 𝐛 Trans - remember all 3 𝐛s are on the same plane
\ | /
M
/ | \
𝐛 | 𝐛
a

    a   𝐛    |    𝐛    Cis
 \  |  /
    M
 /  |  \   a    |    a
    𝐛