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 Cu+2 Cu+ Au+

Ag+ Zn+2 Ni+2

Pt+2 Co+2 Al+3

Ligands•The negative ions or polar molecules bound by the central element

in a complex ion

Ligand Examples•Cl- F- H2O•NH3 CN- Br-

•NO 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

-O2C-CO2-

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:

H2Oaqua

NH3amine CO carbonyl NO 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

[Co(H2O)2Cl4]-2

[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 octa- T-shaped octa- bis: 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 o(splitting energy)

Field Strength Largeo yields low spin or diamagnetic

compds

Field Strength Smallo yields high spin or paramagnetic

compds

[Pt(NH3)2I4]-2

Determine: Name, shape, &

possible isomerism

[Co(NH3)6]+3 yellow[Co(NH3)5NCS]+2 orange[Co(NH3)5H2O]+2 red[Co(NH3)5Cl]+2 purplet-[Co(NH3)4Cl2]+1 green

Complex Ion Equilibria

Cu+2 + 4 NH3 [Cu(NH3)4]+2

[Cu(NH3)4]+2

[Cu+2][NH3]4Kf =

Calculate the ratio of [Cu+2]/ [Cu(NH3)4]+2 when Cu+2 is added to a 0.10 M

NH3 solution:Kf = 2.0 x 1012

Common Ion Equilibria

•The larger the Kf, the more likely the complex will form

Common Ion Equilibria•Kf for [Ag(NH3)2]+1

= 1.7 x 107

•Kf for [Ag(CN)2]-1

= 2.0 x 1020

Common Ion Equilibria•Kf for [M(NH3)2]+2

= 1.7 x 107

•Kf for [M(CN)4]-2

= 2.0 x 1020

Common Ion Equilibria

CN- will replaceNH3 in the

complex with silver

Calculate: a) coordination #

b) number of isomersc) oxidation # of metal

[Zn(NH3)2H2OF]+1

[Co(NH3)3ClFI]-1