have different positions of groups
with respect to a double bond or ring
or central atom (see illustration).
Octahedral complexes can display
cis-trans isomerism if they have formulae of the type MX 2 Y 4 . Octahedral
complexes with formulae of the type
MX 3 Y 3 can display a different type of
isomerism. If the three X ligands are
in a plane that includes the metal
atom and the three Y ligands are in a
different plane at right angles, then
isomerism
296
i
1-chloropropane
H
C
C
C
C I
H
H
H
H
H
H
H
C
C
C
H
H
H
CI
H
H
H
2-chloropropane
structural isomers in which the functional group has different positions
methoxymethane
ethanol
structural isomers in which the functional groups are different
trans-but-2-ene
cis-but-2-ene
cis–trans isomers in which the groups are distributed on a double bond
cis–trans isomers in a square-planar complex
H
C
O
C
H
H
H
H
H
H
C
C
O H
H
H
H
H
H
C H 3
C
C
CH 3
H
CH 3
C
C
H
H
CH 3
keto form
enol form
C
C
O
C
C
OH
CI
I
CI
I
Pt
I
C I
CI
I
Pt
keto–enol tautomerism
Isomerism
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