Transition Metals
Transition metal – a metal that can form one or more stable ions with an incomplete d subshell
The incomplete d subshell is responsible for a number of general properties of transition metals
o Form complexes
o Form coloured compounds
o Variable oxidation states
o Catalytic action
Complex Ions
Ligand – particle with a lone pair of electrons that bonds to metal by a co-ordinate bond
Complex – a metal ion with co-ordinately bonded ligands
Co-ordination number – number of co-ordinate bonds from ligands to the metal
Lewis base – lone pair donor
Lewis acid – lone pair acceptor
The ligand acts as the Lewis base as it donates the lone pair, whilst the metal ion acts as the
Lewis acid as it accepts the lone pair
All ligands must have one or more lone pairs of electrons to form the co-ordinate bond to the
metal ion
Unidentate ligands – ligands which form one co-ordinate bond to a metal ion
o H2O, OH–, NH3, CN–, Cl–
Bidentate ligands – ligands which form two co-ordinate bonds to the metal ion
o 1,2-diaminoethane
o
o Ethanedioate ion
o
Multidentate ligands – ligands which form more than two-co-ordinate bonds to a metal ion
o EDTA4– (6 bonds)
o
, o
o Porophyrin (Haemoglobin, 4 bonds)
o
o
Haemoglobin
Globular protein containing four Fe2+ centres, each with a porphyrin ligand taking up four of the
six co-ordination sites
Other site is bonded to the rest of haemoglobin leaving one site to which oxygen can bond as a
ligand
Oxygen is carried around the body in blood bonded to iron in haemoglobin in this way
Cyanide compounds and carbon monoxide are toxic as they are better ligands than oxygen so
bond to the Fe2+ and prevent oxygen being transported around the body
Shapes of Complexes
Linear
o Co-ordination number – 2
o Occurance – Ag complexes
Square planar
o Co-ordination number – 4
o Occurance – Pt and Ni complexes
Tetrahedral
o Co-ordination number – 4
o Occurance – Cl– ligands
Octahedral
Transition metal – a metal that can form one or more stable ions with an incomplete d subshell
The incomplete d subshell is responsible for a number of general properties of transition metals
o Form complexes
o Form coloured compounds
o Variable oxidation states
o Catalytic action
Complex Ions
Ligand – particle with a lone pair of electrons that bonds to metal by a co-ordinate bond
Complex – a metal ion with co-ordinately bonded ligands
Co-ordination number – number of co-ordinate bonds from ligands to the metal
Lewis base – lone pair donor
Lewis acid – lone pair acceptor
The ligand acts as the Lewis base as it donates the lone pair, whilst the metal ion acts as the
Lewis acid as it accepts the lone pair
All ligands must have one or more lone pairs of electrons to form the co-ordinate bond to the
metal ion
Unidentate ligands – ligands which form one co-ordinate bond to a metal ion
o H2O, OH–, NH3, CN–, Cl–
Bidentate ligands – ligands which form two co-ordinate bonds to the metal ion
o 1,2-diaminoethane
o
o Ethanedioate ion
o
Multidentate ligands – ligands which form more than two-co-ordinate bonds to a metal ion
o EDTA4– (6 bonds)
o
, o
o Porophyrin (Haemoglobin, 4 bonds)
o
o
Haemoglobin
Globular protein containing four Fe2+ centres, each with a porphyrin ligand taking up four of the
six co-ordination sites
Other site is bonded to the rest of haemoglobin leaving one site to which oxygen can bond as a
ligand
Oxygen is carried around the body in blood bonded to iron in haemoglobin in this way
Cyanide compounds and carbon monoxide are toxic as they are better ligands than oxygen so
bond to the Fe2+ and prevent oxygen being transported around the body
Shapes of Complexes
Linear
o Co-ordination number – 2
o Occurance – Ag complexes
Square planar
o Co-ordination number – 4
o Occurance – Pt and Ni complexes
Tetrahedral
o Co-ordination number – 4
o Occurance – Cl– ligands
Octahedral
