Metal Ligand

1. Know your syllabus: Module 8: Applying Chemical Ideas
Topic: Analysis of Inorganic Substances
Inquiry question: How are the ions present in the environment identified and measured?
● conduct qualitative investigations – using flame tests, precipitation and complexation reactions as
appropriate – to test for the presence in aqueous solution of the following ions:
– cations: barium (Ba2+), calcium (Ca2+), magnesium (Mg2+), lead(II) (Pb2+), silver ion (Ag+), copper(II)
(Cu2+), iron(II) (Fe2+), iron(III) (Fe3+)
– anions: chloride (Cl–), bromide (Br–), iodide (I–), hydroxide (OH–), acetate (CH3COO–), carbonate
(CO32–), sulfate (SO42–), phosphate (PO43–)

3. Transition Metals (d block elements)
Across period
Cr - 4s13d5
• half filled more stable
Cu - 4s13d10
• fully filled more stable
Ca
4s2
K
4s1
Transition metal have partially filled 3d orbitals
•3d and 4s electrons can be lost easily
• electrons filled from 4s level first then 3d level
• electrons lost from 4s level first then 3d level
• 3d and 4s energy level close together (similar in energy)
Filling electrons- 4s level lower, filled first Losing electrons- 4s higher, lose first
3d
4s

4. Transition Metals
• d block elements with half/partially filled d orbitals/sublevels in one or more of its oxidation states
•
Transition Metals (d block elements)
Incomplete filled d orbitals
Lose Ions
Electrons formation
Sc3+
4s03d0
Zn2+
4s03d10
Zn not transition elements.
•Zn → Zn2+ - (fully filled d orbital)
4s2
3d10 4s0
3d10
Sc not transition elements.
•Sc → Sc3+ - (empty d orbital)
4s2
3d1 4s0
3d0

5. http://elementalolympics.wordpress.com/2011/02/28/variable-oxidation-states-and-catalysts/
http://www.chemguide.co.uk/inorganic/transition/features.html
Properties of Transition metals
• Formation of complex ions
• Formation coloured complexes
• Variable oxidation states
• Catalytic activity
• Ions are paramagnetic (unfilled
electron shell)
Transition Metals (d block elements)
Formation coloured complexes
Formation complex ions
Variable Oxidation states
http://www.dlt.ncssm.edu/tiger/chem8.htm
Catalytic activity
http://www.sciencelearn.org.nz/Contexts/Nanoscience/
Sci-Media/Images/Catalytic-converter-catalyst

6. Transitional metal ions tend to form coloured complexes while normal metals do not.

7. Transition Metals (d block elements) – Formation Complex Ions
2+
2CI-
Complex ion – [Cu(H2O)4]CI2
Transition Metal ion
• High charged density metal ion, partially filled 3d orbital
• Attract ligand (neutral, anion with lone pair electron)
• Form dative/co-ordinate bond – lone pair from ligands
CI2
Complex ion
• 4 water ligands attached
• 4 dative bonds
• Coordination number = 4
Drawing complex ion
• Overall charged on complex ion outside
of brackets
• Metal ion in the center (+ve charged)
• Ligands attached
• Dative bonds from ligands
+
water
[Cu(H2O)4]CI2 [Cu(H2O)4]2+ + 2CI-
Ligands
• Neutral/anion species that donate
lone pair/non bonding electron pair to metal ion
• Lewis base, lone pair donor – dative bond with metal ion
• Coordination number – number of ligands around central ion
Transition Metal ion + Ligands = Complex Ions
Anion
+2

8. Check your understanding
Recap on the equilibrium of covbalt:
Equlibrium and Cobalt Complex Ions |
Chemistry Minute - YouTube

9. Naming Complex ions
Step in naming complex ion - [Co(NH3)4CI2]+CI-
Tetraamine dichloro cobalt (III)
(cation part)
1. Cation part first → anion part later
2. Within a complex metal – ligands named first followed by metal ion
3. Name - Tetraamine dichloro cobalt (III) chloride
Chloride
(anion part)
Step in naming complex ion - [Cu(H2O)4]2+CI2
Tetraaqua copper (II)
(cation part)
1. Cation part first → anion part later
2. Within a complex metal – ligands named first followed by metal ion
3. Name - Tetraaqua copper(II) chloride
Chloride
(anion part)
Step in naming complex ion - [Co(H2O)6]2+SO4
Hexaaqua cobalt(II)
(cation part)
1. Cation part first → anion part later
2. Within a complex metal – ligands named first followed by metal ion
3. Name – Hexaaqua cobalt (II) sulphate
Sulphate
(anion part)
Step in naming complex ions with TWO different ligands
1. Name ligand (alphabetical order)
2. [Cu(NH3)4(H2O)2]2+ - tetraammine diaqua copper(II) ion. (1st ligand- ammine, 2nd ligand aqua)
3. [Al(H2O)2(OH)4]- - diaqua tetrahydroxo aluminate ion. (1st ligand – aqua, 2nd ligand hydroxo)

10. Taken from: http://www.chm.bris.ac.uk/webprojects2003/rogers/998/chemlab.htm
• Why transition metals ion complexes have different colour?
Transition Metals (d block elements) – Coloured Complexes

11. Colour formation due to splitting of 3d orbitals of metal ion by ligands
Transition Metals (d block elements) – Coloured Complexes
Absence of ligands
• 3d orbitals same energy level
• five 3d orbitals are equal in energy
http://www.chemistryland.com/CHM151W/07-Atomic%20Structure/ElectronConfig/ElectronConfiguration.html
Five 3d orbitals
Five 3d orbitals
Splitting 3d orbitals
No ligands
• No splitting of 3d orbitals
• 3d orbitals equal energy
With ligands
• Splitting of 3d orbitals
• 3d orbitals unequal energy
Splitting 3d orbitals
• 3d orbitals split into different energy level
• Electronic transition possible
• Photon of light absorbed to excite electrons
Why Titanium (III) ion solution is violet ?
violet
Link to crystal field theory
Presence of ligands
• 3d orbitals split
• five 3d orbitals unequal in energy
Extension

12. Why Titanium (III) ion solution is violet ?
Transition Metals (d block elements) – Coloured Complexes
Ti3+ transmit blue/violet region BUT absorb green/yellow/red
Light in vis region
Ground state Ti3+ (3d1)
Ti3+ absorb green/yellow/red photons
to excite electrons to higher level
Ti3+ transmit
blue/violet region
Electron excited

13. Cu2+ transmit blue/violet BUT absorb /orange/red region
Transition Metals (d block elements) – Coloured Complexes
Why Copper (II) ion solution is blue ?
Light in vis region
Ground state Cu2+ (3d9)
Cu2+ absorb orange/red photons
to excite electrons to higher level
Cu2+ transmit
blue/violet region
Electron excited
Cu2+ appears blue
• Complementary colour (Red/Orange) are absorbed to excite electron
• Blue colour is transmitted

14. Transition metal have different colours due to
• splitting of 3d orbitals by ligands
• partially filled 3d orbitals for electron transition
CuSO4 (anhydrous) without ligands - Colourless
Why some are colourless ?
Cu2+ anhydrous – colourless
Cu1+ hydrous – colourless
Zn2+ hydrous – colourless
Sc3+ hydrous – colourless
Transition Metals (d block elements) – Coloured Complexes
No ligands
No splitting of 3d orbitals
No electron transition
No colour
Ground state Cu2+ (3d9)
Ligands split the 3d orbitals
Electron transition from
lower to higher level by
absorbing ∆E
CuSO4 (hydrous) with H2O ligands – Blue Colour
NO Colour
Colour
[Cu(H2O)6]2+ SO4 – splitting 3d orbitals by ligand – Blue colour

15. Transition Metals (d block elements) – Coloured Complexes
Sc 3+ ion with ligands - Colourless
Zn2+ ion with ligands - Colourless
Ground state Sc3+ (3d0)
Ligands split the 3d orbitals
No electrons in 3d orbital
No electron transition
NO Colour
[Sc(H2O)6]3+ CI3
• Empty 3d orbitals
• No colour
Ground state Zn2+ (3d10)
Ligands split the 3d orbitals
Fully filled in 3d orbital
No electron transition
NO Colour
[Zn(H2O)6]2+ SO4
• Filled 3d orbitals
• No colour

17. Check your understanding