1. Transition Metal Chemistry The Chemistry of the d-block elements

2. The Periodic Table s p d

3. Electronic configurations 1s 2, 2s 2, 2p 6, 3s 2, 3p 6, 4s 2, 3d 6 1s 2, 2s 2, 2p 6, 3s 2, 3p 6, 4s 2, 3d 10 1s 2, 2s 2, 2p 6, 3s 2, 3p 6, 4s 2, 3d 1 Using the aufbau principle:

4. The two exceptions You would expect Chromium to have the electronic configuration: 1s 2, 2s 2, 2p 6, 3s 2, 3p 6, 4s 2, 3d 4 But in fact it has the configuration: 1s 2, 2s 2, 2p 6, 3s 2, 3p 6, 4s 1, 3d 5 There is a special stability associated with half-filled and full sub- shells. Copper: 1s 2, 2s 2, 2p 6, 3s 2, 3p 6, 4s 1, 3d 10

5. Ions Transition metals are defined as metallic elements with an incomplete d sub-shell in at least one of their ions. Form positive (+) ions by losing electrons. These electrons come from the 4s sub-shell first, then from the 3d sub-shell: 1s 2, 2s 2, 2p 6, 3s 2, 3p 6, 4s 2, 3d 6 Fe atom: 1s 2, 2s 2, 2p 6, 3s 2, 3p 6, 3d 6 Fe 2+ ion:

6. Complex Ions and Complexes Understanding Transition metal compounds

7. In aqueous solution Transition metal ions exist as complex ions in aqueous solution, e.g. Co(H 2 O) 6 2+ What shape is this?

9. Ligands The water molecules are an example of ligands LIGAND: molecules or anions which attach to the metal atom in a complex via coordinate (dative) covalent bonds Number of bonds formed with ligands = COORDINATION NUMBER Assemble is known as a COMPLEX ION So instead of existing in solution as free ions, e.g. Cu 2+, exist as complex ions, Cu(H 2 O) 5 2+ Formed through donation of electron pairs Coordinate covalent bond

10. Shapes of complex ions

11. Naming ligands LigandName Bromide Carbonate Cyanide Hydroxide Ammonia Carbon monoxide Water Bromo Carbonato Cyano Hydroxo Ammine Carbonyl Aqua

12. Categories of ligand MONODENTATE LIGAND: the ligand bonds to the metal using one atom POLYDENTATE LIGANDS: the ligand bonds to the metal using more than one atom

14. Common Examples ChlorophyllHaemoglobin

15. Determining coordination number Complex ionCoordination number Ag(NH 3 ) 2 + HgI 3 - W(CO) 6 4+ 236236 6 is the most common coordination number Number of bonds formed with ligands = COORDINATION NUMBER

16. Forming a complex The cation or anion cannot exist on their own and must have their charges balanced The complex ion will bond with oppositely charged ions to form a complex ComplexCationAnion [Pt(NH 3 ) 6 ]Cl 4 [Pt(NH 3 ) 4 Cl 2 ]Cl 2 K 4 [Fe(CN) 6 ] Pt(NH 3 ) 6 4+ Pt(NH 3 ) 4 Cl 2 2+ K + Cl - Fe(CN) 6 4-

17. Naming Coordination Compounds 1.Cation precedes anion 2.Complex ion names are one word: ligands first, then metal 3.Ligands will have a Greek prefix in front 4.If the complex ion is an anion, it ends in -ate 5.The metal name is followed by the oxidation state in Roman Numerals

18. Old vs New CuSO 4 ·5H 2 O vs [Cu(H 2 O) 5 SO 4 ] Copper(II) sulphate pentahydrate Pentaaquacuprum(II) sulphate

19. Colour in Transition Metal Compounds

20. Why coloured? Transition metal ions are often coloured They absorb EM radiation because of loss of degeneracy of d-orbitals Those which absorb in the visible region will appear the complementary colour

21. The 5 d-orbitals in an isolated atom are degenerate Ligands cause the d-orbitals to become non- degenerate Different ligands cause different splitting effects

22. Crystal field splitting (energy), Δ

23. In an octahedral complex, the ligands lie on the x, y and z axis Their electrons have a greater repulsive effect on the d-orbitals which lie on the same axis

24. Spectrochemical Series An arrangement of ligands according to the relative magnitudes of the crystal field splittings they induce in the d-orbitals of a metal ion I - < Br - < Cl - < F - < OH - < H 2 O < NH 3 < NO 2 - < CN - < CO Weak-bonding ligandsStrong-bonding ligands Increasing Δ Therefore, different ligands will result in different colours

25. Gemstones Cr 3+ in Al 2 O 3 Cr 3+ in Be 3 Al 2 (SiO 3 ) 6

26. Catalysis Transition metals as catalysts

27. Catalysts provide an alternative pathway with a lower activation energy Transition metals can use half-filled or empty orbitals to form intermediate complexes (e.g. 4p) They can change oxidation state during a reaction, then revert back to their original state