Transition metals

1. Objective
A comprehensive knowledge of transition elements
chemistry will be gained by understanding the
structure of metals and coordination compounds.

2. Transition Metals
Occupy the d-block of periodic table
Have d-electrons in valence shell
Some characteristics of Transition Metals and their
compounds
1. Exhibit more than one oxidation state
2. Many of their compounds are colored
3. They exhibit interesting magnetic properties.
4. They form an extensive series of compounds
known as metal complexes or coordination
compounds.

3. e.g., Reduction of V5+ by metallic Zn
VO2(H2O)4
+ yellow-orange
VO(H2O)5
2+ blue
V(H2O)6
3+ green
V(H2O)6
2+ violet
Exhibit more than one oxidation state
Many of their compounds are colored
Transition Metals

4. ELECTRON CONFIGURATIONS
3d elements: Sc  Zn
Ar 3s23p6 Sc [Ar]3d14s2
K [Ar]4s1 Ti [Ar]3d24s2
Ca [Ar]4s2 . .
. .
. .
Zn [Ar]3d104s2
Note: 4s is filled before 3d, but when oxidized, 4s electrons are lost
before 3d.
Ti [Ar]3d24s2
Ti2+ [Ar]3d24s0
Ti3+ [Ar]3d14s0
Ti4+ [Ar]3d04s0
Ti5+ does not exist!

5. TRANSITION METALS: ScMn
Oxidation States:
Highest oxidation states of Sc, Ti, V, Cr, Mn = number of
valence (4s + 3d) electrons.
Sc [Ar]3d14s2 Sc3+ [Ar] maximum
Mn [Ar]3d54s2 Mn7+[Ar] maximum
Trend from Sc  Mn:
The max. oxidation state becomes increasingly unstable.
Sc3+, Ti4+ are stable (maximum oxidation states).
Sc2O3 Stable oxide.
Mn7+ Exists but is easily reduced.
MnO4
- Strong oxidizing agent.
Transition Metals

6. Magnetic Properties
Diamagnetic:
unaffected by a magnetic field
no unpaired electrons
Paramagnetic:
influenced by a magnetic field
unpaired electrons
Transition metals and their compounds are often
paramagnetic
Have unpaired d-electrons
Eg. Ti2+
Mn2+

7. Nomenclature &
Coordination Chem

8. Lewis Acid - Lewis Base Chemistry
•Lewis Acid : e- acceptor
• (metals are good e- acceptor)
•Lewis Base : e- donor
• (Ligands with lone pair electrons)
•Ligands, atoms or cluster of atoms with
lone pair electrons available to donate
•Complexing Agent: H2O, NH3, Cl- CN-

9. Complex -
•Metal- Ligand compounds
• [MLn] i.e., [Ag(NH3)2]+ or [Co(NH3)6] Cl3
•[ ] denotes atoms bonded to each other
through covalent bonds. These atoms are
contained in the coordination sphere.
Coordinated sphere is the directly bonded to each other.
Counter ions are outside bracket, and are not part of the coordinate
sphere.
A coordinated compound behaves like an electrolyte in water: the
complex ion and counter separates from each other. But the complex
ion behaves like a polyatomic ion: the ligands and central metal ion
remain attached.

10. Coordinated Complexes and Coordination
Number
•Coord Shape Example
•Number
• 2 Linear [CuCl2]-, [Ag(NH3)2]+, [AuCl2]-
• 4 Square Planar [Ni(CN)4] 2-, [PdCl4]2-
• [Pt(NH3)4] 2+, [Cu(NH3)4] 2+
• 4 Tetrahedral [Cu(CN)4] 3-, [Zn(NH3)4]2+
• [CdCl4] 2-, [MnCl4] 2-
• 6 Octahedral [Cu(H2O)6] 3+, [V(CN)6] 4-,
• [Cu(NH3)4Cl2] +, [Co(en)3] 3+
F
F
Br
F
F
F
F
F
S
F
F
F

11. Ligands
• Example of Typical mono-, bi- and poly dentate Ligands
Name of Neutral and Anionic Ligands:
Neutral: Anionic
Aqua H2O Fluoro Fl
-
Amine NH3 Chloro Cl
-
Nitrosyl NO Bromo Br-
Carbonyl CO Iodo I
-
Hydroxo OH
-
Cyano CN
-

12. Chelates
• Chelating Ligands have two or more donor atoms that
simultaneously coordinate to a single metal ion.
• Polydentate - (Many toothed - ligand)
• Chelating agent (Claw)
• Sequestering agent - sequester - to set apart or
separate
• en ethylenediamine (shown) - two toothed ligand:
– i.e., [Co(en)3]3+ [Pt(en)2]2+
• EDTA ethylenediaminetetraacetate
– (picture) hexadentate
– EDTA is the antidote for
– heavy metal poisoning

13. Chelating agents in Living system
•Seven of 24 elements necessary for life,
based on ability to formed complexes
• V, Cr, Mn, Fe, Co, Cu, Zn
•Fe - hemoglobin, chlorophyll (Mg)
•Co - Vitamin B

14. Biological Coordinating Complexes
• Chlorophyll
• Oxymyoglobin Ferrichrome

15. Nomenclature
• Cation - Anion: Salts: name cation before anions i.e.,
[Co(HN3)5Cl]Br2, we name [Co(HN3)5Cl] complex ion before bromides
counter ions .
• Complex: Within complex ion, the ligands are named in alphabetical
order before the metal i.e., pentaaminechlorocobalt(II), note that tetra is
an indication of the number of NH3 group, and not considered in the
alphabetizing of the ligand.
• Ligand: Anionic ligands end in -o and neutral ligands are name based
on their molecular name (excepts are aqua H2O, amine: NH3)
–Greek prefixes are used to indicate number of ligands, di-, tri-, tetra-,
penta-, hexa-. Exception occurs when ligand already has Greek prefix
in its name, The prefixes bis-, tris-, tetrakis-, pentakis, & hexakis. are
used instead.
– i.e., Ir(bpy)3 trisbipyridineiridium (III) bipyridine already has bi in its
name.
• If the complex is an anion, then its name ends with suffix -ate.
• Further more, oxidation state of the metal is given in roman numerals in
parenthesis at the end of the name.

16. Nomenclature
• Rules:
• 1. The cation is written before the anion.
• 2. The charge of the cation(s) is balanced by the charge of the
anion(s).
• 3. For the complex ion, neutral ligands are written before
anionic ligands (negative charge), and the whole ion is
placed in brackets.
• Procedure Outline:
• 1. The cation is named before the anion.
• 2. Within the complex ion, the ligands are named, in alphabetical
order.
• 3. Neutral ligands generally have the molecule name.
• Anionic ligands drop the -ide and add -o after the root
name.
• 4. Numerical prefixes denote the number of a particular ligand.
• 5. Oxidation state of metal ion is in Roman numeral in
parenthesis.
• 6. For anionic complex, the end of the metal name is replaced by
-ate.

17. Example: Naming from Formula
• Name from formula
• a) K3[Au(CN)4]
• Potassium Tetracyanoaurate(I)
• d) K[Co(C2O4)2(NH3)2]
• Potassium diaminedioxaloCobaltate(I)
• f) [Cr(en)2F2]NO3
• Bis(ethylenediamine)difluorochromium(III) nitrate
• Naming anionic metals
• Iron: Ferrate Copper: Cuprate
• Lead: Plumbate Silver:
Argentate
• Gold: Aurate Tin: Stannate

18. Example: Formula from Name
• Name from formula
• a) Hexaamminechromium(III) nitrate
• [Cr(NH3)6] (NO3)3
• d) dichlorobis(ethylenediamine)platinum(IV) bromide
• [PtCl2(en)2]Br2
• f) bis(ethylenediamine)zinc(II) tetraiodomercurate(II)
• [Zn(en)2][HgI4]
•
• More anionic metals
• Osmium: Osmate Cobalt: Cobaltate
• Amtimony: Antimonate Rhenium:
Rhenate
• Platinum: Platinate Rhodium: Rhodate

19. Co
F
F F
F F
F
Co3+ Co3+
F- F-
F-
F-
F-
F-
(3d6)
CRYSTAL FIELD SPLITTING

20. CRYSTAL FIELD SPLITTING
dx2-y2 dz2
dxy dyz dxz

 = crystal field splitting energy
Spectrochemical series:
CN > NO2
 > en > NH3 > H2O > OH- > F > Cl
decreasing 
d-electron
energy

21. COLOR WHEEL
RED
GREEN
VIOLET
ORANGE
YELLOWBLUE

23. SPIN PAIRING
OCTAHEDRAL COMPLEXES
E
CoF6
3-
Co(CN)6
3-
High spin
Paramagnetic Low spin (spin paired)
diamagnetic