1. The document discusses properties of coordination compounds including electronic spectra, hydration energies, lattice energies, and ionic radii as determined by crystal field theory. 2. Crystal field theory can be used to determine the splitting of d-orbital energies under the influence of ligands in an octahedral or tetrahedral field and explain observations from electronic spectra. 3. Hydration energies and lattice energies of metal ions can also be explained using crystal field theory calculations and comparisons to experimental data. 4. Crystal field theory further explains trends in ionic radii and the structures of spinel compounds containing mixed metal oxides.

1. Properties of
Coordination Compounds
Part 1 (1/3)
Applications of Crystal Field Theory
Dr.Christoph Sontag
University of Phayao 2018

2. 3 types of metal compounds
Electronic Spectra
Hydration energies
Lattice energies
Ionic radii
Spinels

3. Factors determining the type of bonds
(1) Oxidation number of the metal
ox.no. 0 indicates a
covalent M-L bond
(2) Coordination number
-> Coordination compounds show the
appropriate number of ligands, in contrast to
ionic compounds
Cu(SO4) as salt and as
coordination compound:

4. Common Coordination numbers
early middle Co-Ni late
4 6 4 2

5. https://www.slideshare.net/MohammedIsmail251/theory-of-
coordinationcompounds1

6. (1) Name of cation (potassium)
(2) Name of ligands in alphabetical order
with numbering “di” “tri” “tetra” “penta” “hexa”
Change anion ligand names to ending “-o”
(Cl- -> chloro, CN- -> cyano, C2O4
2- -> oxalato)
(3) Name the metal and add ox.number
Metal is in an anion -> add “ate”
(nickelate, cobaltate, cuprate, ferrate)
Metal is in cation or
neutral part -> metal
name

7. Examples
K4 [Fe(CN)6]
potassium hexa cyano Ferrate (II)
(NH4)2 [Ni(C2O4)2 (H2O)2]
ammonium diaqua bisoxalato Nickelate (II)

12. Name and category of compound ?
Fe(CO)5 ox.no. cat:
FeCl3 ox.no. cat:
(in water: pH 3)
K3Fe(CN)6 ox.no. cat:
CuSO4 ox.no. cat:
Cu(CN) 4
(2-) ox.no. cat:
Cu(OAc)2
(2-) ox.no. cat:

13. Example
A) [Cr(NH3)3Cl3]
B) [Cr(NH3)6]Cl3
C) Na3[Cr(CN)6]
D) Na3[CrCl6]
Which of these compounds will form
a precipitation with AgNO3 ?

14. Review: CFT
Applications of Crystal Field Theory

15. Crystal Field Theory Review
http://wwwchem.uwimona.edu.jm/courses/CFT.html

16. http://www.youtube.com/watch?v=LydEaN8-WJ8

17. Spectrochemical series

18. Conclusions from CFT

19. Extension: LFT
How many valence
electrons are in the
molecule when all
bonding and non-
bonding orbitals are
filled ?

20. pi-donor ligands => low splitting

21. pi-acceptor ligands => high splitting

22. Symmetry Symbols
http://www.webqc.org/symmetrypointgroup-td.html

23. Which symmetry do the 5 d-orbitals in a tetrahedron have ?

24. Conclusions from LFT

25. (1) Find the configuration (as tx
2gey
g / ext2
y), the number of
unpaired electrons and the LFSE (in terms of ∆o / ∆t and P)
(2) Which of the following complexes has higher LFSE:
(h) [MnF6]3- i) [NiBr4]2- j) [Fe(CN)6]4-

26. Applications of CFT
(1) Electronic spectra
(2) Hydration energies
(3) Lattice energies
(4) Ionic radii
(5) Spinel types

27. (1) Electronic Spectra (example)
Each peak in the spectrum (λ <-> ν ) corresponds to a change
in the electronic state (Shriver/Atkins p.576)

28. Find ∆o from Tanabe-Sugano diagrams
∆/B
E/B
V(H2O)6
2+ shows 2 peaks at
17200 and 25600 cm-1
(1) Get E-ratio: E2/E1 = 1.49
(2) Find by trial and error this ratio
in the diagram => ∆/B
we find here a value of 40/27 = 29
(3) From this we find B:
E2 = 25600 = 40 *B
E1 = 17200 = 27 *B => B = 640 cm-1
(4) When B is know, then
∆o = 29 * 640 cm-1 = 18600 cm-1

29. http://www.chem.uky.edu/courses/che610/JPS_Spring_2007/
PS2_2007key.pdf
Self-study:

30. Energy ratios:
E2/E1 = 1.8
E3/E1 = 3.05
E3/E1 = 1.68
Now we move on the x-axis until
we find this ratio in the y values
again (approximately !)
=> ∆/B = 10
from that we get B:
E3/B = 29 (graph) => B = 896 cm-1
=> ∆o = 10 * 896 cm-1 = 8960 cm-1
(more exact: take the average for all 3 found B values)

32. (2) Hydration energies
http://www.youtube.com/watch?v=awD1qa7TF4A

34. (3) Lattice energies
Experimental data vs. calculated for MCl2 high-spin
compounds according to the Born-Haber Cycle

35. (4) Ionic Radii M(2+) --- O

36. M2+ ions in water are in a weak field => they are all high-spin
Then we get 2 minima in the radii at V2+ with 3 electrons in the t2g
levels and Ni2+ with 6 electrons in t2g
For low-spin there is only one minima at Fe2+ with 6 electrons in t2g

37. (5) Spinels (gemstones)
Spinels = crystals formed by mixed oxides,
originally used for MgAl2O4
In a closed packed solid, there are tetrahedral and
octahedral “holes” filled with a metal ion.
“ cubic closed packing”
(https://www.youtube.com/watch?v=U_n7DyCqv6U)

38. Example
What is the oxidation number of Fe in Fe3O4 ?

39. “normal”: A in Td , B in Oh holes
Fe3O4 is a spinel type : Fe2+ (Fe3+ )2 O4
“inverse”: A in Oh,
1/2B in Td and 1/2B in Oh
(neglectpairingenergyP)
http://www.everyscience.com/Chemistry/Inorganic/
Crystal_and_Ligand_Field_Theories/e.1016.php
“Magnetite”

40. If M3+ has a higher CFSE than M2+ in an octahedral
field, these ions will prefer octahedral holes and
forms a “normal” spinel.
Predict the structure for Mn3O4

41. Applications for Spinels
Spinel Ferrites M2+ Fe3+
2 O4
Fe-O framework
Spinel Aluminates M2+ Al3+
2 O4
Al-O framework

42. https://www.youtube.com/watch?v=U_n7DyCqv6U

45. Visualization of molecules and orbitals
www.chemtube3d.com

46. 3D structures of crystals
Fe(2+)
Fe(3+)