Transition metals• Produce compounds with at least one stable oxidation

state with a partially filled d-orbital• Zn (4s2 3d10) Zn2+ (3d10) NOT TM• Cu (4s1 3d10) Cu2+ (3d9) TM• Transition metals: electron shells• Compounds are often coloured – absorption spectra

by electrons transitioning between split d-orbital• d-orbitals split by ligands. • Full/empty d orbital: no transition possible so no colour

absorbed• Different ligands different colours• Multiple oxidation states: Ions form by losing d-

electrons little change in radius extra ionisation energy ≈ extra lattice energy

Vanadium

• +5 VO2+

• +4 VO2+

• +3 V3+ [V(H2O)6]3+

• +2 V2+ [V(H2O)6]2+

• Note: oxo-ions for high oxidation states

Conversion between vanadium oxidation states

2VO2+(aq) + 4H+(aq) + 2e – 2VO2+ (aq) + 2H2O (l)

SO32 – (aq) + H2O (l) SO4

2 – (aq) + 2H+(aq) + 2e – (aq)

2VO2+(aq) + SO3

2 – (aq) + 2H+(aq) 2VO2+ (aq) + SO42 – (aq) + H2O (l)

2VO2+(aq) + 4H+(aq) + 2e – 2VO2+ (aq) + 2H2O (l)

Zn(s) Zn2+ (aq) + 2e –

2VO2+(aq) + 4H+(aq) + Zn(s) 2VO2+ (aq) + Zn2+ (aq) + 2H2O (l)

2VO2+ + 2e – + 4H+ (aq) 2V3+ (aq) + 2H2O (l)

Zn(s) Zn2+ (aq) + 2e –

2VO2+ + Zn(s) + 4H+ (aq) 2V3+ (aq) + Zn2+ (aq) + 2H2O (l)

2V3+(aq) + 2e – 2V2+ (aq)

Zn(s) Zn2+ (aq) + 2e –

2V3+(aq) + Zn(s) 2V2+ (aq) + Zn2+ (aq)

Deprotonation and ligand exchange

• Deprotonation[Cu(H2O)6]2+ (aq) + 2 OH- Cu(OH)2(H2O)4 (s) + 2 H2O

A H+ ion is removed from the hydrating water

• Ligand exchangeCu(OH)2(H2O)4 (s) + 4 NH3 [Cu(NH3)4(H2O)2]2+ (aq) + 2 H2O + 2 OH-

The NH3 swaps places with the ligands

Identification of metal ions• Flame tests – see AS!

• + OH-: drops followed by excess (DEPROTONATION)Cu2+ - pale blue ppt; remains

Fe2+ - dirty green ppt; remains (slowly oxidises)

Fe3+ - foxy brown ppt; remains

Ni2+ - green ppt; remains

Mn2+ - beige ppt; remains

Cr3+ - green ppt; soluble

Zn2+ - white ppt; dissolves

Identification of metal ions• + NH3: drops followed by excess

(DEPROTONATION then LIGAND EXCHANGE)Cu2+ - pale blue ppt; dissolvesFe2+ - dirty green ppt; remains (slowly oxidises)Fe3+ - foxy brown ppt; remainsNi2+ - green ppt; dissolvesMn2+ - beige ppt; remainsCr3+ - green ppt; dissolves (?)Zn2+ - white ppt; dissolves

Hydrated metal ions

Cu

OHH

OH

H

OH

HO

HH

OHH

OH

H

Dative bond

Covalent bond

2+

Hexaaquacopper (II) ion

Hydrated metal ions

Cu

OHH

OH

HO

HH

OHH

Dative bond

Covalent bond

(s)

O-H

O-H

Cu

2+

NH3

NH3

H3N

H3N

OHH

OHH

Tetraamminediaquacopper (II) ion

Complex ionsCu2+ - [Cu(H2O)6]2+ (aq); Cu(OH)2 (s); [Cu(NH3)4(H2O)2]2+

(aq)Fe2+ - Fe(H2O)6

]2+ (aq); Fe(OH)2 (s) Fe(OH)2 (s)

Fe3+ - Fe(H2O)6]3+ (aq); Fe(OH)3 (s)

Ni2+ - [Ni(H2O)6]2+(aq); Ni(OH)2 (s); [Ni(NH3)6]2+ (aq)

Mn2+ - [Mn(H2O)6]2+ (aq); Mn(OH)2 (s)

Cr3+ - [Cr(H2O)6]3+ (aq); Cr(OH)3 (s); [Cr(OH)6]3- (aq); [Cr(NH3)6]3+ (aq)

Zn2+ - [Zn(H2O)6]2+ (aq); Zn(OH)2 (s); [Zn(OH)4]2- (aq) [Zn(NH3)4]2+ (aq)

Transition metals: + OH-

Some other complex ions

• Tetrachlorocuprate (II) [CuCl4]2-

• Hexacyanoferrate (II) [Fe(CN)6]4-

• Hexacyanoferrate (III) [Fe(CN)6]3-

• Potassium hexacyanoferrate (III) K3[Fe(CN6)]

• Tetrachlorochromate (III) [CrCl4]-

• Dichlorocuprate (I) [CuCl2]-

• Diamminedichloroplatinum (II) Pt(NH3)2Cl2

Shapes of complex ions• Similar to covalent molecules:

– 6 pairs of electrons: octahedrale.g. Cr(NH3)6]3+ and [Cu(H2O)6]2+

– 4 pairs of electrons: tetrahedrale.g.[CuCl4]2- and [CrCl4]-

– 4 pairs of electrons: square planare.g. Pt(NH3)2Cl2

2 pairs of electrons: lineare.g. [CuCl2]- [ClCuCl]-

Ligands• Form complex ions by donating a pair of

electrons

L:M

• Can be monodentate (e.g. H2O, NH3, CN- or Cl-) or polydentate (e.g. 1,2-diaminoethane H2NCH2CH2NH2, EDTA or ethanedioate ion C2O4

2-)