1. Advanced Higher Chemistry Unit 1 Transition metal complexes

2. Transition Metal Complexes n A transition metal complex consists of a transition metal ion surrounded by ligands. n A ligand is a molecule or negative ion that binds to the transition metal ion by donating one or more electron pairs to the unfilled orbitals of the metal ion.

3. Monodentate Ligands n Monodentate ligands are ligands that donate one electron pair. n Water and ammonia are neutral ligands which bond to the metal ion by a lone pair of electrons. n Cyanide (CN - ), halides (e.g.Cl - ), nitrite (NO 2 - ) and hydroxide (OH - ) ions are common negative ligands.

4. Bidentate Ligands n Bidentate ligands provide two pairs of electrons. n Two examples of bidentate ligands are: - ethanedioate (oxalate - C 2 O 4 2- ) C 2 O 4 2- ) - 1,2-diaminoethane

5. EDTA n Ethylenediaminetetraacetic acid (EDTA) is a hexadentate ligand which can complex with many transition metals (e.g.Ni) in a 1:1 ratio.

6. Co-ordination Number n The number of ligands that can surround a transition metal ion can vary. n The number of bonds from the ligand to the metal ion is known as the co-ordination number. n [Cu(H 2 O) 6 ] 2+ : co-ordination number of Cu = 6 n [CuCl 4 ] 2- : co-ordination number of Cu = 4

7. Co-ordination Number and shape Coordination number Shape 2linear 4 square planar 4tetrahedral 6octahedral

8. Naming complex ions n The metal symbol is written first followed by negative ligands and finally neutral ligands e.g. [Fe(OH) 2 (H 2 O) 4 ] + n The formula should be written in square brackets with the overall charge following the brackets. n Ligands are named first in alphabetical order. n ‘-ide’ becomes ‘o’ (e.g.chloride > chloro). n ‘-ite’ becomes ‘ito’ (e.g.nitrite > nitrito).

9. n If the ligand is water it is named aqua, ammonia is named ammine and carbon monoxide is carbonyl. n More than one ligand is prefixed by di, tri, tetra, penta or hexa. n If the complex ion is a negative ion the suffix ‘ate’ is added to the name of the metal. n The latin name is often used for iron (ferrate NOT ironate) and copper (cuprate NOT copperate). n The oxidation state of the metal is given in Roman Numerals after its name e.g. [Ni(NH 3 ) 6 ] 2+ is called hexaamminenickel(II) and [Fe(CN) 6 ] 3- is called hexacyanoferrate(III).

10. Exercise n Now try the exercise on page 19 of the Unit 1(c) notes. n You are now able to complete Unit 1 PPA 1