Coordination Compounds

They are always double the primary valencies

They are directed toward fixed positions in space

They are satisfied by protons

They change when the compound is dissolved in water

0.1 mole

0.2 mole

0.3 mole

0.0 mole

Coordination Polyhedron

Primary Geometry

Ionization Sphere

Valence Shell

$[Co(NH_3)_6]Cl_3$

$[Co(NH_3)_5Cl]Cl_2$

$[Co(NH_3)_4Cl_2]Cl$

$[Co(NH_3)_3Cl_3]$

4

6

2

0

Secondary valency

Primary valency

Coordination number

Oxidation state of Cobalt

$[Ni(NH_{3})_{6}]Cl_{2}$

$[Fe(H_{2}O)_{6}]Cl_{3}$

$[Pt(NH_{3})_{2}Cl_{2}]$

$K_{2}[PtCl_{6}]$

$PtCl_{4} \cdot 6NH_{3}$

$PtCl_{4} \cdot 5NH_{3}$

$PtCl_{4} \cdot 4NH_{3}$

$PtCl_{4} \cdot 3NH_{3}$

2

4

6

0

Secondary valencies are non-ionizable

Primary valency is satisfied by anions

Secondary valency is directional and determines geometry

Primary valency is satisfied by neutral molecules

Tetrahedral

Square planar

Octahedral

Trigonal bipyramidal

$CN^-$

$Ni^{2+}$

$Ni^{0}$

$Ni^{4+}$

Unidentate ligand

Chelating ligand

Ambidentate ligand

Monodentate ligand

$Cl_3$

$[Co(NH_3)_6]$

$Co^{3+}$

$NH_3$

Ligands

Counter ions

Coordination entity

Chelating agents

Nitrito-O

Nitrito-N

Nitrosyl

Nitroso

Ethane-1,2-diamine

Oxalate

Ethylenediaminetetraacetate

Glycinate

Double salts exist only in the solid state and dissociate into simple ions in water; complexes retain their identity in solution.

Double salts contain only one type of cation; complexes contain two.

Complexes are always colored; double salts are always white.

Double salts follow Werner's theory; complexes do not.

$+2$

$+3$

$+4$

$+8$

The region containing the central metal ion

The ligands directly bonded to the metal

The portion of the compound that dissociates in aqueous solution

The spatial arrangement of the ligands

Potassium trichlorido(ethene)platinate(II)

Potassium trichlorido(ethene)platinum(II)

Potassium trichlorido(ethylene)platinate(IV)

Ethenetrichloridoplatinate(II) potassium

Tetraaquadichloridochromium(III) chloride

Tetraaquadichloridochromate(III) chloride

Dichloridotetraaquachromium(III) chloride

Tetraaquadichloridochromium(II) chloride

Tetraamminepalladium(II) chloride

Tetraamminepalladium(IV) chloride

Tetraamminepalladate(II) chloride

Tetraamminepalladium(0) chloride

Tetraamminedichloridochromium(III) ion

Tetraamminedichloridochromate(III) ion

Dichloridotetraamminechromium(III) ion

Tetraamminedichloridochromium(II) ion

Hexaamminecobalt(III) hexacyanidochromate(III)

Hexaamminecobalt(II) hexacyanidochromate(IV)

Hexaamminecobaltate(III) hexacyanidochromium(III)

Hexaamminecobalt(III) hexacyanidochromium(III)

Pentaamminesulfatocobalt(III) chloride

Pentaamminesulfatocobalt(II) chloride

Sulfatopentaamminecobalt(III) chloride

Pentaamminesulfatocobaltate(III) chloride

Trioxalatoferrate(III) ion

Trioxalatoiron(III) ion

Tris(oxalato)ferrate(III) ion

Trioxalatoferrate(II) ion

Tetraamminecopper(II) sulfate

Tetraamminecopper(I) sulfate

Tetraamminecuprate(II) sulfate

Tetraamminecopper(II) sulfite

Potassium pentacyanidonitrosylferrate(II)

Potassium pentacyanidonitrosylferrate(III)

Potassium pentacyanonitrosyliron(II)

Potassium pentacyanidonitrosyliumferrate(II)

Sodium dicyanidoargentate(I)

Sodium dicyanidosilver(I)

Sodium dicyanoargentate(I)

Sodium dicyanidoargentate(II)

Optical isomerism

Linkage isomerism

Geometrical isomerism

Hydrate isomerism

Linkage isomerism

Ionization isomerism

Optical isomerism

Coordination isomerism

2

3

4

0

$CN^-$

$Cl^-$

$H_2O$

$NH_3$

2

3

4

5

All three $Cl$ ligands are $cis$ to each other

Two $Cl$ ligands are $trans$ to each other

The complex is optically active

The complex is square planar

Silver nitrate solution

Barium chloride solution

Both Silver nitrate and Barium chloride solutions

Neither Silver nitrate nor Barium chloride

4

6

8

12

$[Co(NH_3)_5(NO_2)]^{2+}$ and $[Co(NH_3)_5(ONO)]^{2+}$

$[Co(NH_3)_5Cl]SO_4$ and $[Co(NH_3)_5SO_4]Cl$

$[Cr(H_2O)_6]Cl_3$ and $[Cr(H_2O)_5Cl]Cl_2 \cdot H_2O$

$[Pt(NH_3)_2Cl_2]$ and $[Pt(NH_3)_4][PtCl_4]$

0

1

2

4

$NH_3$

$CO$

$H_2O$

$Cl^-$

$t_{2g}^3 e_g^2$

$t_{2g}^5 e_g^0$

$t_{2g}^4 e_g^1$

$t_{2g}^2 e_g^3$

$s$ and $p$ orbitals

$t_{2g}$ and $e_g$ orbitals

Metal and ligand orbitals

Inner and outer $d$ orbitals

High spin complexes

Diamagnetic complexes

Paramagnetic complexes with 4 unpaired electrons

Tetrahedral complexes

$18000 \\text{ cm}^{-1}$

$8000 \\text{ cm}^{-1}$

$40000 \\text{ cm}^{-1}$

$9000 \\text{ cm}^{-1}$

$3.87 \\text{ BM}$

$4.90 \\text{ BM}$

$1.73 \\text{ BM}$

$2.83 \\text{ BM}$

$[CoF_6]^{3-}$

$[NiCl_4]^{2-}$

$[Fe(CN)_6]^{4-}$

$[MnCl_4]^{2-}$

$-936 \\text{ kJ/mol}$

$-516 \\text{ kJ/mol}$

$-726 \\text{ kJ/mol}$

$-1146 \\text{ kJ/mol}$

$-0.4 \\Delta_o$

$-2.4 \\Delta_o + 2P$

$-1.2 \\Delta_o$

$-2.4 \\Delta_o + 3P$

They point directly at the ligands

They are $d_{x^2-y^2}$ and $d_{z^2}$

They are lower in energy than the $e_g$ orbitals

They are doubly degenerate

$[Ni(CO)_4]$

$[Fe(CO)_5]$

$[Cr(CO)_6]$

None of these

$\\pi$ bond

$\\sigma$ bond

Delta bond

Ionic bond

Nickel

Iron

Chromium

Cobalt

Increase

Decrease

Stay the same

Disappear

$1.050\ \text{\AA}$

$1.110\ \text{\AA}$

$1.128\ \text{\AA}$

$1.150\ \text{\AA}$

They are highly soluble in water

They are soluble in non-polar organic solvents

They are insoluble in all solvents

They only dissolve in concentrated acids

$[Ni(CO)_4]$ because Nickel is more electronegative

$[Fe(CO)_4]^{2-}$ because of greater back-donation

Both are identical

$[Ni(CO)_4]$ because it is tetrahedral

4

5

6

4.5 (dimerizes)

fac-isomer

mer-isomer

Both show the same number of bands

Neither is IR active

1.0

2.0

3.0

3.5

Dissociates into ions in water

Formed from its components in equilibrium

Precipitates from the solution

Conducts electricity

$Cu^{2+}$ is larger than $Ni^{2+}$

$Cu^{2+}$ is smaller than $Ni^{2+}$

$Cu^{2+}$ has fewer electrons

$Cu^{2+}$ is a hard acid

Chelate effect

Macrocyclic effect

Template effect

Steric effect

$Fe^{3+}$

$Fe^{2+}$

$Ba^{2+}$

$Cu^{2+}$

$5.0 \times 10^{12}$

$2.0 \times 10^{-13}$

$5.0 \times 10^{-14}$

$1.0 \times 10^{-13}$

The ligand contains double bonds

The ligand is saturated (no double bonds)

The metal ion is very large

The metal ion is in a low oxidation state

$-91.8 kJ/mol$

$-45.9 kJ/mol$

$-183.6 kJ/mol$

$-22.9 kJ/mol$

Potentiometric titration (pH-metry)

Spectrophotometric methods (Job's method)

Conductometric titration

All of the above

Statistical factors and increased steric repulsion

A change in the geometry from octahedral to tetrahedral

A change in the electronic configuration of $Cd^{2+}$

The decrease in the basicity of the $NH_3$ ligand

The $en$ complex has a higher $\Delta_o$, contributing to its higher stability

The $en$ complex is more labile

The $NH_3$ complex has a higher CFSE

The $en$ complex is a high-spin complex

Ethylene diamine tetraacetic acid

Ethylene diamine triacetic acid

Ethylene diacetate tetraamine

Ethyl diamine triacetate

Rhodium

Titanium

Platinum

Nickel

Low boiling point

High solubility in organic solvents

Formation of stable soluble complexes

High density

Acidic

Ammoniacal

Strongly basic

Neutral

Increased stability due to monodentate ligand substitution

Increased stability due to the formation of cyclic structures by multidentate ligands

Decreased stability due to steric hindrance

Stability resulting from the presence of water molecules

Ammonia

Tartrate ions

Citrate ions

EDTA

Increase the calcium level in the blood

Treat metal poisoning by exchanging $Ca^{2+}$ for more toxic ions like $Pb^{2+}$

Inhibit the clotting of blood

Reduce the acidity of the stomach

The cobalt complex $[Co(DMG)_3]$ is soluble in water, whereas the nickel complex $[Ni(DMG)_2]$ is an insoluble neutral chelate.

Cobalt does not react with DMG at all.

The nickel complex is octahedral, while the cobalt complex is tetrahedral, making nickel more reactive.

DMG is a stronger oxidizing agent than $Co^{2+}$.

Linear

Tetrahedral

Square Planar

Trigonal Planar

It polarizes the ethene molecule to allow radical attack.

It holds the ethene in a specific orientation for insertion into the Titanium-Carbon bond.

It reduces the Titanium to its metallic state.

It acts as a chain terminator.