Complex Ions

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Complex Ions
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Complex Ion

• An ion formed when a positive central element
  binds with multiple ions or polar molecules

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Complex Ion

• The central element is almost always a positively
  charged metal

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Describe or define a Complex Ion
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Anion

• Negatively charged ion

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Cation

• Positively charged ion

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Metal Ion Examples

• Cu2 Cu Au
• Ag Zn2 Ni2
• Pt2 Co2 Al3

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Ligands

• The negative ions or polar molecules bound by the
  central element in a complex ion

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Ligand Examples

• Cl- F- H2O
• NH3 CN- Br-
• NO O2 OH-

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Polydentate Ligands

• Ligands that can bind to more than one point

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Bidentate Ligands

• Ligands that can bind to two points in a complex
  ion

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Bidentate Examples

• H2N-CH2-CH2-NH2
• -O2C-CO2-

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Tridentate Ligands

• Ligands that can bind to three points in a
  complex ion

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Tridentate Examples

• H2-C-COO-
• HO-C-COO-
• H2-C-COO-

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Chelates

• Polydentate ligands that bind to metal ions in
  solution

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Coordination Number

• The number of points in which ligands bind to the
  central element in a complex ion

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Coordinate Covalent Bond

• Covalent bonds in which both electrons involved
  are donated by one atom

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Complex Ions

• The bonds formed in a complex ion are coordinate
  covalent bonds

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Coordination Complex

• A complex ion and its counter ion

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Complex Ions

• The bonds formed in a complex ion are coordinate
  covalent bonds

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Complex Ion

• Because of the type bonding, they are sometimes
  called coordinate complexes

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• 1) Name cations before anions

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Naming Complexes

• 2) Name ligands before metal in the complex ion

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2) Naming Ligands

• a) give neutral compds normal names except

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• H2O aqua
• NH3 amine
• CO carbonyl
• NO nitrosyl

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2) Naming Ligands

• b) change -ide endings to -o for all anions

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2) Naming Ligands

• d) use geometric prefixes for monodentate ligands

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2) Naming Ligands

• e) use bis- for 2 tris- for 3 polydentate
  ligands

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3) Naming Metal

• a) use the normal name if the complex ion is ()

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3) Naming Metal

• b) make the metal ending -ate if the complex ion
  is (-)

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3) Naming Metal

• d) use Roman numerals in () to indicate metal ox

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Name the Following

• Pt(NH3)4Cl2
• Co(H2O)2Cl4-2
• Cu(H2O)2(en)2I2

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Predict of isomers of each

• Pt(NH3)4 Cl2
• Co(H2O)3Cl3

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Complex Ion Shapes

• 2-linear
• 4-tetrahedral or sq pl
• 6-octahedral

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Geometric Isomers

• Square planar vs tetrahedral
• cis vs trans

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Geometric Isomers

• Bunched octa-
• T-shaped octa-
• bis cis vs trans

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Optical Isomers

• Tri-bis mirror images

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Field Strength

• CN- gt NO2- gt en gt NH3 gt NCS- gt H2O gt F- gt Cl-

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Field Strength

• CN- is strong field
• Cl- is weak field

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Field Strength

• Determines d-level splitting or Do(splitting
  energy)

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Field Strength

• Large Do yields low spin or diamagnetic compds

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Field Strength

• Small Do yields high spin or paramagnetic compds

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Pt(NH3)2I4-2

• Determine
• Name, shape, possible isomerism

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Co(NH3)63 yellow Co(NH3)5NCS2
orange Co(NH3)5H2O2
red Co(NH3)5Cl2
purple t-Co(NH3)4Cl21 green
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Complex Ion Equilibria
Cu2 4 NH3 Cu(NH3)42
Cu(NH3)42 Cu2NH34
Kf
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Calculate the ratio of Cu2/ Cu(NH3)42 when
Cu2 is added to a 0.10 M NH3 solutionKf
2.0 x 1012
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Common Ion Equilibria

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

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Common Ion Equilibria

• Kf for Ag(NH3)21
• 1.7 x 107
• Kf for Ag(CN)2-1
• 2.0 x 1020

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Common Ion Equilibria

• Kf for M(NH3)22
• 1.7 x 107
• Kf for M(CN)4-2
• 2.0 x 1020

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Common Ion Equilibria
CN- will replace NH3 in the complex with silver
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Calculate a) coordination b) number of
isomersc) oxidation of metal

• Zn(NH3)2H2OF1
• Co(NH3)3ClFI-1