Complex Ions

1. Complex Ions Naming and Formula Writing

2. Definitions • Complex ion – A combination of a metal ion and a ligand • Ligand – Group bonded to a metal ion • Coordination Compound – A neutral compound containing a complex ion • Ligands you must know • OH- Hydroxo • CN-Cyano • SCN-Thiocyano • H2O Aqua • NH3 Ammine (yes, with 2 m’s) • F-, Br-, Cl- , I-Fluoro, Bromo, Chloro, Iodo

3. Naming • The name begins with the ligand. Use your prefixes to tell how many of the ligand are present. • Then name the metal ion. • If the overall charge of the complex ion is positive, place the charge of the metal ion in ( ) even if we have never done it before….Al (III) • If the overall charge of the complex ion is negative, use the Latin form of the metal, if applicable, then add –ate and ( ) for the charge of the metal.

4. Trying a Few [Al(OH)4]- There are four hydroxo, therefore, begin with Tetrahydroxo The overall complex ion is negative, so the metal is named aluminate. The Al has a charge of 3+, because the OH- and there are four of them and the overall charge = - Name: tetrahydroxoaluminate (III) ion

5. Another One [Ag(NH3)2]+ Ligand = diammine Metal = silver (complex ion is +) Metal charge = +, as the NH3 is neutral Name: diammine silver (I) ion

6. One More [Ag(CN)2]- Ligand = dicyano Metal = argentate (complex ion is -) Name: dicyanoargentate (I) ion

7. How do you know how many ligands to add? • As a general rule, the number of ligands you attach to a metal ion will equal 2 times the charge of the metal ion. • Example: • Al3+ with the ligand OH- [Al(OH)6]3-hexahydroxo aluminate (III) ion • Example: • Cu2+ with the ligand NH3 [Cu(NH3)4]2+tetraammine copper (II) ion