Complex
Ions
Complex Ion
•An ion formed when a
positive central element
binds with multiple ions
or polar molecules
Complex Ion
•The central
element is almost
always a positively
charged metal
Describe or
define a
Complex Ion
Anion
•Negatively
charged ion
Cation
•Positively
charged ion
Metal Ion Examples
+2
Cu
+
Cu
+
Au
+
Ag
+2
Zn
+2
Ni
+2
Pt
+2
Co
+3
Al
Ligands
•The negative ions or
polar molecules bound
by the central element
in a complex ion
Ligand Examples
•Cl
F
H2 O
•NH3
•NO
CN
Br
O2
OH
Polydentate
Ligands
•Ligands that can
bind to more than
one point
Bidentate
Ligands
•Ligands that can
bind to two points
in a complex ion
Bidentate
Examples
H2N-CH2-CH2-NH2
-O
C-CO
2
2
Tridentate Ligands
•Ligands that can
bind to three points
in a complex ion
Tridentate
Examples
H2-C-COO
HO-C-COO
H2
-C-COO
Chelates
•Polydentate
ligands that bind
to metal ions in
solution
Coordination Number
•The number of points
in which ligands bind
to the central element
in a complex ion
Coordinate
Covalent Bond
•Covalent bonds in
which both electrons
involved are donated
by one atom
Complex Ions
•The bonds formed in
a complex ion are
coordinate covalent
bonds
Coordination
Complex
•A complex ion and
its counter ion
Complex Ions
•The bonds formed in
a complex ion are
coordinate covalent
bonds
Complex Ion
•Because of the type
bonding, they are
sometimes called
coordinate complexes
1) Name cations
before anions
Naming Complexes
2) Name ligands
before metal in the
complex ion
2) Naming Ligands
a) give neutral
compds normal
names except:
H2O
NH3
CO
NO
aqua
amine
carbonyl
nitrosyl
2) Naming Ligands
b) change -ide
endings to -o for
all anions
2) Naming Ligands
d) use geometric
prefixes for
monodentate
ligands
2) Naming Ligands
e) use bis- for 2 &
tris- for 3
polydentate ligands
3) Naming Metal
a) use the normal
name if the
complex ion is (+)
3) Naming Metal
b) make the metal
ending -ate if the
complex ion is (-)
3) Naming Metal
d) use Roman
numerals in () to
indicate metal ox #
Name the Following:
[Pt(NH3)4]Cl2
-2
[Co(H2O)2Cl4]
[Cu(H2O)2(en)2]I2
Predict # of isomers
of each:
[Pt(NH3)4 Cl2]
[Co(H2O)3Cl3]
Complex Ion Shapes
2-linear
4-tetrahedral or sq pl
6-octahedral
Geometric Isomers
Square planar vs
tetrahedral
cis vs trans
Geometric Isomers
Bunched octaT-shaped octabis: cis vs trans
Optical Isomers
Tri-bis mirror
images
Field Strength
CN > NO2 > en >
NH3 > NCS >
H2O > F > Cl
Field Strength
CN is strong field
Cl is weak field
Field Strength
Determines d-level
splitting or
Do(splitting energy)
Field Strength
Large Do yields
low spin or
diamagnetic
compds
Field Strength
Small Do yields
high spin or
paramagnetic
compds
-2
]
[Pt(NH3)2I4
Determine:
Name, shape, &
possible isomerism
+3
]
[Co(NH3)6
+2
[Co(NH3)5NCS]
+2
[Co(NH3)5H2O]
+2
[Co(NH3)5Cl]
+1
t-[Co(NH3)4Cl2]
yellow
orange
red
purple
green
Complex Ion Equilibria
+2
Cu
+ 4 NH3
Kf =
[Cu(NH3)4
+2
]
+2
]
[Cu(NH3)4
+2
4
[Cu ][NH3]
Calculate the ratio of
+2
+2
[Cu ]/ [Cu(NH3)4]
+2
when Cu is added to a
0.10 M NH3 solution:
12
Kf = 2.0 x 10
Common Ion Equilibria
•The larger the Kf,
the more likely the
complex will form
Common Ion Equilibria
•Kf for [Ag(NH3)2
7
= 1.7 x 10
-1
•Kf for [Ag(CN)2]
20
= 2.0 x 10
+1
]
Common Ion Equilibria
•Kf for [M(NH3)2
7
= 1.7 x 10
-2
•Kf for [M(CN)4]
20
= 2.0 x 10
+2
]
Common Ion Equilibria
CN
will replace
NH3 in the
complex with silver
Calculate:
a) coordination #
b) number of isomers
c) oxidation # of metal
+1
OF]
[Zn(NH3)2H2
-1
[Co(NH3)3ClFI]