1. Complexes

2. Complexes
Compounds in which a metal atom or ion is surrounded by a number of oppositely charged ions or by neutral molecules. All possessing lone pairs of electrons which are available for donation to vacant orbitals of the metal atom or ion.

3. [Hexaammineplatinum(IV)] chloride
Structure 1.
[Hexaammineplatinum(IV)] chloride
central ion
coordination number
ligand
[Pt(NH3)6]Cl4
complex cation

4. Potassium hexachloroplatinate(IV)2.
Potassium hexachloroplatinate(IV)
K2[PtCl6]
central ion
coordination number
ligand
complex anion

5. Iron(O)pentacarbonyl3.
Iron(O)pentacarbonyl
central atom
coordination number
ligand
[Fe(CO)5]
complex molecule

6. Central ions, atoms:
Transition metals
Alkaline earth metals
Alkaline metals
Coordination numbers:
Number of ligands in the first
coordination sphere

7. Complexes with various coordination numbers2
[Ag(NH3)2]+, [CuCl2]- 3
[HgI3]- 4
[Zn(NH3)4]2+, [Ni(CN)4]2- 5
[Ni(CN)5]3-, Fe(CO)5 6
[Cr(H2O)6]3+, [Fe(CN)6]3- 7
[ZrF7]3- 8
[Mo(CN)8]4-

8. Geometry:
linear (2)
tetrahedral (4)
square planar (4)
octahedral (6)

9. Monodentate Ligands Cations: H2N-NH3+ Anions:
F-, Cl-, OH-, CN-, NO3-, NO2-
Neutral molecules:
H2O, NH3, CO

10. Water
Ammonia
Chloride ion
Cyanide ion
Carbon monoxide
Thiocyanate ion
Hydroxide ion

11. Polydentate Ligands Ethylenediamine (en) Glycinate ion (gly-)
Oxalate ion
Ethylenediaminetetraacetate ion (EDTA4-)

12. Chelates
Bi- or polydentate ligands
Men+

13. Nomenclature: IUPAC Cation preceeds anions
Ligands preceed central ions or atoms
Anion ligands: -o ending (hydroxo, chloro, cyano…)
Cations, neutral molecules: unchanged
Exception(!): aqua, ammine, carbonyl, nitrosyl
Complex anions: -ate ending
Oxidation state: Roman numbers

14. Dissociation of complexes
Formula
Conductance*
Number of ions
Number of
chloride ions
[Pt(NH3)6]Cl4
523 5 4
[Pt(NH3)5Cl]Cl3
404 3
[Pt(NH3)4Cl2]Cl2
228 2
[Pt(NH3)3Cl3]Cl 97 1
[Pt(NH3)2Cl4]
K[Pt(NH3)Cl5]
108
K2[PtCl6]
256
*Molar conductance:
cm2/·mól, 0,001M, 25°C

15. Stability constant, formation
Properties of metal complex differ from metal ion!
Colour changing
Solubility
Ligand reactions
Number of particles, dissociation
Formation constant: Kstab (stability constant)
Pl.: Ag+ + 2NH [Ag(NH3)2]+
[Ag(NH3)2]+
[Ag+][NH3]2
= 1,7·107
K =
Dissociation constant:
[Kstab] 1
Kd =

16. Constitutional isomers
Izomerism
Constitutional isomers
Enantiomers
Ionization isomers
Diastereoisomers
Stereoisomers
Linkage isomers
Isomers

17. CrCl3·6H2O
[Cr(H2O)6]Cl [Cr(H2O)4Cl2]Cl·2H2O
[Cr(H2O)5Cl]Cl2·H2O

18. [dichloro-tetraammine-cobalt(III)] ion
cis
trans
NH3 Cl Co 
NH3 Cl Co 
[dichloro-tetraammine-cobalt(III)] ion

19. [dichloro-bis(etylenediammine)cobalt(III)] ionCl Co en Cl Co en
[dichloro-bis(etylenediammine)cobalt(III)] ion
en = etylenediammine

20. Bonding in complexes:
Valence Bond Theory
Crystal Field Theory