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1. Presenter
Usama Waheed
Roll no 16103123-032
A.o.A
COORDINATION
COMPOUND

2. Coordination compounds
• Consist of a complex ion and necessary counter ions
• [Co(NH3)5Cl]Cl2
•
• Complex ion: [Co(NH3)5Cl]2+
• Co3+ + 5 NH3 + Cl-
• = 1(3+) + 5 (0) + 1(1-)
• = 2+
• Counter ions: 2 Cl-

3. Coordination compouds
Early chemists approached transition metal complexes
using the concept of “valences” adapted from main
group metals. Metals with a +3 charge, such as
iron(III) or cobalt(III) were believed to only make
three bonds.
A compound such as [Co(NH3)6]Cl3 was thought
to have three Co-Cl bonds, with no way to explain the
bonding of ammonia in the compound.

4. Coordination compouds
One approach by Blomstrand proposed chains of
linked ammonia molecules, with the nitrogens having
five bonds and connecting a chloride to the metal.
Alfred Werner proposed that the ammonia
molecules could bond strongly and directly to the
metal, with chlorides either directly bonded, or
loosely bonded and ionic in solution.

5. Coordination compounds
•Jorgensen supported Blomstrand’s approach, and
Werner, in order to support his theory, synthesized
new compounds and studied their isomers.
Eventually, in 1907, Werner prevailed and proved the
octahedral geometry of coordination compounds

6. Coordination compounds
•Alfred Werner (1866-1919) also determined the
formulas and structures of many transition metal
compounds by studying their isomers. Due to the
existence of a variety of structural isomers, he
proposed that complexes must have square planar
and octahedral shapes.

7. Geometry Of Coordination Compounds

8. A Ligand
• Molecule or ion having a lone electron pair that can be used to form
a bond to a metal ion
• (Lewis base).
• coordinate covalent bond: metal-ligand bond
• monodentate: one bond to metal ion
• bidentate: two bond to metal ion
• polydentate: more than two bonds to a metal
• ion possible

9. Names of Common Ligands
Formula Name
Br- bromo
CO3
2- carbonato
Cl- chloro
CN- cyano
H- hydrido
OH- hydroxo
O2- oxo

10. Formulas of Coordination Compounds
• 1. Cation then anion
• 2. Total charges must balance to zero
• 3. Complex ion in brackets
• K2[Co(NH3)2Cl4]
• [Co(NH3)4Cl2]Cl

11. Simple Naming Coordination Compounds
[Co(NH3)5Cl]Cl2
1. Cation is named before the anion. “chloride” goes last
2. Ligands are named before the metal ion. ammine, chlorine
named before cobalt
3. For ligand, an “o” is added to the root name of an anion (fluoro,
bromo). For neutral ligands the name of the molecule is used,
with exceptions. ammine, chloro
4. The prefixes mono-, di-, tri-, etc., are used to denote the number
of simple ligands. penta ammine

12. Simple Naming Coordination Compounds
[Co(NH3)5Cl]Cl2
5. The oxidation state of the central metal ion is designated by a
(Roman numeral).
cobalt (III)
6. When more than one type of ligand is present, they are
named alphabetically.
pentaamminechloro
7. If the complex ion has a negative charge, the suffix “ate” is
added to the name of the metal.
pentaamminechlorocobalt (III) chloride

14. 20_441
Isomers
(same formula but different properties)
Stereoisomers
(same bonds, different
spatial arrangements)
Structural
isomers
(different bonds)
Optical
isomerism
Geometric
(cis-trans)
isomerism
Linkage
isomerism
Coordination
isomerism

15. Structural Isomerism 1
• Coordination isomerism:
• Composition of the complex ion varies.
• [Cr(NH3)5SO4]Br
• and [Cr(NH3)5Br]SO4

16. Structural Isomerism 2
• Ligand isomerism:
• Same complex ion structure but point of attachment of at
least one of the ligands differs.
• [Co(NH3)4(NO2)Cl]Cl
• and [Co(NH3)4(ONO)Cl]Cl

17. Linkage Isomers
[Co(NH3)5(NO2)]Cl2
Pentaamminenitrocobalt(III)
chloride
[Co(NH3)5(ONO)]Cl2
Pentaamminenitritocobalt(III)
chloride

18. Stereoisomerism 1
• Geometric isomerism (cis-trans):
• Atoms or groups arranged differently spatially relative to
metal ion
• Pt(NH3)2Cl2

20. Stereoisomerism 2
• Optical isomerism:
• Optical isomers are molecules that differ three-dimensionally by the placement of
substituents around one or more atoms in a molecule. Optical isomers were given
their name because they were first able to be distinguished by how they rotated
plane-polarized light.
• (no superimposable mirror images)
20_446
Unpolarized
light
Polarizing
filter
Polarized
light
Tube
containing
sample

Rotated
polarized light

21. 20_448
Left hand
Right hand
Mirror image
of right hand

22. 20_450
Cl
Cl
N
N
N
N
Co
Cl
Cl
N
N
N
N
Co
Cl
Cl
N
N
N
N
Co
Cl
Cl
N
N
N
N
Co
Cl
Cl
N
N
N
N
Co
Isomer IIIsomer I
cistrans
Isomer II cannot be
superimposed exactly
on isomer I. They are
not identical structures.
The trans isomer and
its mirror image are
identical. They are not
isomers of each other.
Isomer II has the same
structure as the mirror
image of isomer I.(b)(a)

23. Thank You For
your attention.