1. The Chemistry of the Transition Elements
Chapter 22

2. Learning Objectives Students understand Students will be able to
Ligand field theory description of metal-ligand bonding in coordination compounds
Students will be able to
Given the formula of a coordination complex, identify the metal and its oxidation state, the ligands, the coordination number and geometry, and the overall charge

3. 22.3 Coordination Compounds
Metallic salts are surrounded by water when they dissolve.
Dipoles in water are attracted to the ions.

4. Complexes and Ligands
Ions in which a metal ion and either water or ammonia molecules compose a unit are examples of coordination compounds or complex ions.
Compounds containing a complex ion as part of their structure are called coordination compounds.

5. Complexes and Ligands
You can write a complex ion as a hydrate, or (more current) as a single structure.
NiCl2•6H2O OR [Ni(H2O)6]Cl2

6. Complexes and Ligands
All coordiation complexes contain a metal atom/ion as the central part of the structure.
Ligands are molecules or ions bonded to the metal.
the number of ligands attached to the metal defines the coordination number

7. Complexes and Ligands
Ligands are usually either neutral molecules or anions. Must have a lone pair of electrons (Lewis base)
The attachment is called a coordinate covalent bond.
Net charge is the sum of the charges on the metal and its attached groups.

8. Formulas of Coordination Complexes
Problem: Give the formulas of the following coordination complex:
A Ni2+ ion is bound to two water molecules and two bidentate (refers to the number of donor atoms) oxalate ions.
This complex ion is constructed from two neutral H2O molecules, two C2O42- ions, and one Ni2+ ion, so the net charge is 2-. The formula is [Ni(C2O4)2(H2O)2]2-.

9. Practice Problem
What is the formula of a complex ion composed of one Co3+ ion, three ammonia molecules, and three Cl- ions?
Determine the metal’s oxidation number and coordination number in (a) K3[Co(NO2)6]
(b) Mn(NH3)4Cl2

10. Naming Coordination Compounds
Name the cation first and then the anion.
For a complex ion, name the ligands first, in alphabetical order (disregard prefix), followed by the name of the metal.

11. Naming Coordination Compounds
Ligands and their names:
If anion is –ite or –ate, the final e is changed to o.
If anion ends in –ide, the ending is changed to o.
If neutral molecule, its common name is used except for water (aqua), ammonia (ammine), and CO (carbonyl).
Use prefixes as needed.

12. Naming Coordination Compounds
If the coordination complex is an anion, the suffix –ate is added to the metal name.
Following the name of the metal, the oxidation number of the metal is given as Roman numerals.

13. Practice Problem Name the following coordination compounds.
[Ni(H2O)6]SO4
K[Pt(NH3)Cl3]
K[CuCl2]

14. Homework
After reading Section 22.3, you should be able to do the following:
P.895 (13-17)