1. Transition Metals and Coordination Compounds
Presented by: Sudhir Kumar Maingi PGT CHEMISTRY
K.V. No. 1 PATHANKOT, JAMMU REGION

2. Gemstones
the colors of rubies and emeralds are both due to the presence of Cr3+ ions – the difference lies in the crystal hosting the ion
Some Al3+ ions in Be3Al2(SiO3)6 are replaced by Cr3+
Some Al3+ ions in Al2O3 are replaced by Cr3+

3. Properties and Electron Configuration of Transition Metals
the properties of the transition metals are similar to each other
and very different tot he properties of the main group metals
high melting points, high densities, moderate to very hard, and very good electrical conductors
in general, the transition metals have two valence electrons – we are filling the d orbitals in the shell below the valence
Group 1B and some others have 1 valence electron due to “promotion” of an electron into the d sublevel to fill it
form ions by losing the ns electrons first, then the (n – 1)d

4. Atomic Size
the atomic radii of all the transition metals are very similar
small increase in size down a column

5. Ionization Energy
the first ionization energy of the transition metals slowly increases across a series
third transition series slightly higher 1st IE
trend opposite to main group elements

6. Electronegativity
the electronegativity of the transition metals slowly increases across a series
except for last element in the series
electronegativity slightly increases down the column
trend opposite to main group elements

7. Oxidation States often exhibit multiple oxidation states vary by 1
highest oxidation state is group number for 3B to 7B

8. Coordination Compounds
when a complex ion combines with counterions to make a neutral compound it is called a coordination compound
the primary valence is the oxidation number of the metal
the secondary valence is the number of ligands bonded to the metal
coordination number
coordination number range from 2 to 12, with the most common being 6 and 4
CoCl36H2O = [Co(H2O)6]Cl3

9. Coordination Compound

10. Complex Ion Formation
complex ion formation is a type of Lewis acid-base reaction
a bond that forms when the pair of electrons is donated by one atom is called a coordinate covalent bond

11. Ligands with Extra Teeth
some ligands can form more than one coordinate covalent bond with the metal atom
lone pairs on different atoms that are separate enough so that both can reach the metal
chelate is a complex ion containing a multidentate ligand
ligand is called the chelating agent

13. EDTA a Polydentate Ligand

14. Complex Ions with Polydentate Ligands

15. Geometries in Complex Ions

16. Naming Coordination Compounds
determine the name of the noncomplex ion
determine the ligand names and list them in alphabetical order
determine the name of the metal cation
name the complex ion by:
name each ligand alphabetically, adding a prefix in front of each ligand to indicate the number found in the complex ion
follow with the name of the metal cation
write the name of the cation followed by the name of the anion

17. Common Ligands

18. Common Metals found in Anionic Complex Ions

19. Isomers
Structural isomers are molecules that have the same number and type of atoms, but they are attached in a different order
Stereoisomers are molecules that have the same number and type of atoms, and that are attached in the same order, but the atoms or groups of atoms point in a different spatial direction

21. Linkage Isomers

22. Geometric Isomers
geometric isomers are stereoisomers that differ in the spatial orientation of ligands
cis-trans isomerism in square-planar complexes MA2B2
cis-trans isomerism in octahedral complexes MA4B2
fac-mer isomerism in octahedral complexes MA3B3

23. Ex. 24.5 – Draw the structures and label the type for all isomers of [Co(en)2Cl2]+
the ethylenediamine ligand (en = H2NCH2CH2NH2) is bidentate
each Cl ligand is monodentate
octahedral
MA4B2

24. Optical Isomers [Co(en)3]3+
optical isomers are stereoisomers that are nonsuperimposable mirror images of each other

25. Ex 24.7 – Determine if the cis-trans isomers of [Co(en)2Cl2]+ are optically active
draw the mirror image of the given isomer and check to see if they are superimposable
cis isomer mirror image is nonsuperimposable
trans isomer identical to its mirror image
no optical isomerism
optical isomers

26. Bonding in Coordination Compounds Valence Bond Theory
bonding take place when the filled atomic orbital on the ligand overlaps an empty atomic orbital on the metal ion
explain geometries well, but doesn’t explain color or magnetic properties

28. Bonding in Coordination Compounds Crystal Field Theory
bonds form due to the attraction of the electrons on the ligand for the charge on the metal cation
electrons on the ligands repel electrons in the unhybridized d orbitals of the metal ion
the result is the energies of orbitals the d sublevel are split
the difference in energy depends the complex and kinds of ligands
crystal field splitting energy
strong field splitting and weak field splitting

29. Splitting of d Orbital Energies due to Ligands in a Octahedral Complex

30. Strong and Weak Field Splitting

31. Complex Ion Color
the observed color is the complimentary color of the one that is absorbed

32. Complex Ion Color and Crystal Field Strength
the colors of complex ions are due to electronic transitions between the split d sublevel orbitals
the wavelength of maximum absorbance can be used to determine the size of the energy gap between the split d sublevel orbitals
Ephoton = hn = hc/l = D

33. Ligand and Crystal Field Strength
the strength of the crystal field depends in large part on the ligands
strong field ligands include: CN─ > NO2─ > en > NH3
weak field ligands include H2O > OH─ > F─ > Cl─ > Br─ > I─
crystal field strength increases as the charge on the metal cation increases

34. Magnetic Properties and Crystal Field Strength
the electron configuration of the metal ion with split d orbitals depends on the strength of the crystal field
the 4th and 5th electrons will go into the higher energy dx2-y2 and dz2 if the field is weak and the energy gap is small – leading to unpaired electrons and a paramagnetic complex
the 4th thru 6th electrons will pair the electrons in the dxy, dyz and dxz if the field is strong and the energy gap is large – leading to paired electrons and a diamagnetic complex

35. Low Spin & High Spin Complexes
diamagnetic
low-spin complex
paramagnetic
high-spin complex
only electron configurations d4, d5, d6, or d7 can have low or high spin

36. Tetrahedral Geometry and Crystal Field Splitting
because the ligand approach interacts more strongly with the planar orbitals in the tetrahedral geometry, their energies are raised
most high-spin complexes

37. Square Planar Geometry and Crystal Field Splitting
d8 metals
the most complex splitting pattern
most are low-spin complexes

38. Applications of Coordination Compounds
extraction of metals from ores
silver and gold as cyanide complexes
nickel as Ni(CO)4(g)
use of chelating agents in heavy metal poisoning
EDTA for Pb poisoning
chemical analysis
qualitative analysis for metal ions
blue = CoSCN+
red = FeSCN2+

39. Applications of Coordination Compounds
commercial coloring agents
prussian blue = mixture of hexacyanoFe(II) and Fe(III)
inks, blueprinting, cosmetics, paints
biomolecules
porphyrin ring
cytochrome C
hemoglobin
chlorphyll
chlorophyll

40. Applications of Coordination Compounds
carbonic anhydrase
catalyzes the reaction between water and CO2
contains tetrahedrally complexed Zn2+
Tro, Chemistry: A Molecular Approach

41. Applications of Coordination Compounds
Drugs and Therapeutic Agents
cisplatin
anticancer drug

42. Thank You Presented by: Sudhir Kumar Maingi PGT CHEMISTRY
K.V. No. 1 PATHANKOT, JAMMU REGION
Phone:
Acknowledgements : Prentice Hall Publications
Steven S. Zumdahl