Complex Ions Naming and Formula Writing

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 H 2 O Aqua NH 3 Ammine (yes, with 2 m’s) F -, Br -, Cl -, I - Fluoro, Bromo, Chloro, Iodo

Naming 1.The name begins with the ligand. Use your prefixes to tell how many of the ligand are present. 2.Then name the metal ion. 1.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) 2.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.

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

Another One [Ag(NH 3 ) 2 ] + Ligand = diammine Metal = silver (complex ion is +) Metal charge = +, as the NH 3 is neutral Name: diammine silver (I) ion

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

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: Al 3+ with the ligand OH - [Al(OH) 6 ] 3- hexahydroxo aluminate (III) ion Example: Cu 2+ with the ligand NH 3 [Cu(NH 3 ) 4 ] 2+ tetraammine copper (II) ion