Download Transition metals and complex ions

Starter
1)
a)
b)
c)
Electronic configuration of:
Sc3+
Fe2+
Cu+
2) Suggest and explain the colour of
compounds containing Zn2+
Transition metals and complex
ions
L.O.:
Explain the term ligand in terms of coordinate
bonding.
Describe and use the terms: complex ion and
coordination number.
 State and give examples of complexes with
six-fold coordination with an octahedral
shape.
Complex ion [Fe(H2O)6]2+
Complex ions - Definations
• LIGAND – molecule or ion that can donate a pair
of electrons to form a coordinate or dative
covalent bond
• COORDINATE BOND – a bond where both
electrons are provided for by the same atom. It is
the same as a dative covalent bond but involves
transition metals instead.
• COMPLEX ION – A transition metal ion bonded to
one or more ligands by coordinate bonds (dative
covalent bonds)
Coordination number
• This is the number of coordinate bonds are
attached to the central metal ion
E.g. [Fe(H2O)6 ]2+
The overall charge of this complex is the sum of
the metal charges and the charges on the ions
that it is coordinated to
Calculate the oxidation number of the metal in:
a) [Cu(NH3)(H2O)]2+
b) [Co(H2O)5Cl]+
Cobalt complex containing 6
monodentate ligands
• Notice the shape adopted by this complex, what
is it and what are the bond angles?
[Co(H2O)6]2+ is an octahedral complex ion
L.O.:
Describe stereoisomerism in transition metal
complexes using examples of cis–trans and
optical isomerism.
Describe the use of cis–platin as an anticancer drug, and its action by binding to
DNA.
Cis–trans isomerism in [Co(NH3)4Cl2]+
Cis–trans isomerism in [NiCl2(NH3)2]
Structure of cis-platin
L.O.:
Explain and use the term: bidentate ligand
(e.g. NH2CH2CH2NH2, ‘en’).
 Describe stereoisomerism in transition
element multidentate complexes using
examples of cis–trans and optical isomerism.
Structure of the ethanedioate ligand, C2O42–
Bidentate: it can
donate two lone
pairs of electrons to
the central metal ion
to form two
coordianate bonds
More bidentate ligands:
ethane-1,2-diamine, NH2CH2CH2NH2
Complex ion [Ni(en)3]2+
Cis–trans isomerism in [Co(NH3)4Cl2]+
Cis and trans isomers of [Cr(C2O4)2(H2O)2]–
Structure of cis-platin
Optical isomers of [Ni(NH2CH2CH2NH2)3]2+
Optical isomerism
Necessary conditions for optical
isomerism
Complexes must have either:
3 bidentate ligands, e.g. [Ni(en)3 ]2+
2 bidentate and 2 monodentate ligands, e.g.
[Co(en)2 Cl2 ]
1 hexadentate ligand – e.g. [Cu(EDTA)]2-
Drawing optical isomers
• First draw the bonds around the metal ion
• Then add the ligands to the first complex
• Then complete the second complex as a
mirror image of the first