5.3.1 transition metals

a d-block element with an incomplete d sub-shell

zinc - forms 2+ ion which has a complete d orbital sc - forms 3+ ion which has an empty d orbital

have more than one oxidation state e.g. Fe2+ and Fe3+ Formation of coloured compounds [Cu(H2O)6]2+ is pale blue, [CuCl4]2- is yellow can act as catalysts e.g. iron in haber process, V2O5 in contact process

transition metal ion bonded to one or more ligands by coordinate bonds (dative covalent bonds)

molecule or ion that can donate a lone pair of electrons to transition metal ion to form a coordinate bond e.g. OH2, NH3, CN-

shared pair of electrons in which the bond pair has been provided by one of the bonding atoms only

number of coordinate bonds formed to a central metal ion

molecule or ion that can donate 2 pairs of electrons with the transition metal ion to form 2 coordinate bonds

[Co(NH3)6]2+ [Cu(H2O)6]2+ many hexaaquo complexes

[CoCl4]2- many tetrachloro complexes

cisplatin PtCl2(NH3)2 complexes of Pt

[Ag(NH3)2]+

used as anti-cancer drug 2 chloride ions are displaced and molecule joins onto the DNA, stopping replication of cancerous cells 1 Cl ligand substituted by water molecule in body

[Cu(H2O)6]2+ + 4Cl- > [CuCl4]2- + 6H2O blue > yellow/green solution

[Co(H2O)6]2+ + 4Cl- > [CoCl4]2- + 6H2O pink > blue solution

blood passes through lungs > haem binds to O2 due to increased O2 pressure in capillaries of lungs > oxyhaemoglobin - releases O2 to body cells haemoglobin can bind to CO2 > carried back to lungs and released

CO2 binds to Fe2+ ion in haem > carboxyhaemoglobin breathing in CO-ligand substitution occurs where O2 in haem is replaced by CO CO binds to haem more strongly than O2, preventing haem from carrying O2 (irreversible) too high of a conc of carboxyhaemoglobin > O2 transport prevented > death