CH# 17 Coordination Chemistry. Transition Metals Transition metals show similarities within a...
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Transcript of CH# 17 Coordination Chemistry. Transition Metals Transition metals show similarities within a...
CH# 17CH# 17Coordination
ChemistryCoordination
Chemistry
Transition MetalsTransition Metals Transition metals show similarities within a period
and a group, different than representative elements Differences can be attributed to the fact that
when electrons are added across a period the valence electrons are not effected.
Therefore group designations are not important here
Behave as metals, strong metallic character
Transition metals show similarities within a period and a group, different than representative elements Differences can be attributed to the fact that
when electrons are added across a period the valence electrons are not effected.
Therefore group designations are not important here
Behave as metals, strong metallic character
Transition MetalsTransition Metals• Some differences– Melting point, Tungsten melts 3400°, while mercury -
39°C– Some soft, like sodium that can be cut with a butter
knife– Reactivity• Some spontaneously react with oxygen like iron,
which flakes off• Others react with oxygen to make a colorless tight
fitting oxide, such as chromium, thus protecting the surface• Some metals are inert to oxygen such as gold, silver
and platinum
• Some differences– Melting point, Tungsten melts 3400°, while mercury -
39°C– Some soft, like sodium that can be cut with a butter
knife– Reactivity• Some spontaneously react with oxygen like iron,
which flakes off• Others react with oxygen to make a colorless tight
fitting oxide, such as chromium, thus protecting the surface• Some metals are inert to oxygen such as gold, silver
and platinum
Transition MetalsTransition MetalsIonic compound formation
More than one oxidation state is often observed
Cations, often are complexes, which we will discuss later in this chapter
Most compounds are colored, since complexes absorb visible light
Many compounds are paramagneticThis chapter will deal specifically the first row transition elements
Ionic compound formation More than one oxidation state is often
observed Cations, often are complexes, which
we will discuss later in this chapter Most compounds are colored, since
complexes absorb visible light Many compounds are paramagneticThis chapter will deal specifically the first row transition elements
Transition ElementsTransition Elements
Electron ConfigurationsElectron ConfigurationsExceptions to the AUFBAU principle
Cr prefers a half full d as opposed to a full 4s, thus 4s13d5
Copper prefers a full 3d as opposed to a full 4s, thus 4s13d10
This half filled, or filled d orbital, is used most of the time to explain this, but other transition metals do not follow this trend.
Exceptions to the AUFBAU principle Cr prefers a half full d as opposed to a full 4s,
thus 4s13d5
Copper prefers a full 3d as opposed to a full 4s, thus 4s13d10
This half filled, or filled d orbital, is used most of the time to explain this, but other transition metals do not follow this trend.
Electron ConfigurationsElectron Configurations
Many texts explain AUFBAU exceptions of chromium and copper as a half full sublevel are more stable than a full 4 s sublevel, or for copper that a full d-sublevel is more stable than a half full 4s
Why is this not the case in periods below?The 4 s and the 3 d orbitals are of about
the same energy or nearly degenerate. Perhaps there is a larger repulsive force in the 4s than in 3d orbitals.
I do not think any one knows, but it is good to think and create right?
Many texts explain AUFBAU exceptions of chromium and copper as a half full sublevel are more stable than a full 4 s sublevel, or for copper that a full d-sublevel is more stable than a half full 4s
Why is this not the case in periods below?The 4 s and the 3 d orbitals are of about
the same energy or nearly degenerate. Perhaps there is a larger repulsive force in the 4s than in 3d orbitals.
I do not think any one knows, but it is good to think and create right?
Electron ConfigurationsElectron Configurations4d and 5d Transition Series– See the size relation on next slide• Decrease in size as we go from left to right, stopping when the d is half full• Significant drop in size going from 3d to 4d, but 4d and 5d remain about the same size–Called Lanthanide contraction–Adding f electrons below the d and the valence shell shel electrons (shielding)–Thus the effect of the increasing size by adding another shell of electrons, which is normally in transition and representative elements, is offset by the shielding of the added f electrons
4d and 5d Transition Series– See the size relation on next slide• Decrease in size as we go from left to right, stopping when the d is half full• Significant drop in size going from 3d to 4d, but 4d and 5d remain about the same size–Called Lanthanide contraction–Adding f electrons below the d and the valence shell shel electrons (shielding)–Thus the effect of the increasing size by adding another shell of electrons, which is normally in transition and representative elements, is offset by the shielding of the added f electrons
Transition Element Sizes
Transition Element Sizes
Oxidation States and IEOxidation States and IE
See common oxidation states on Next slide
The maximum oxidation state for each transition element going across the row is what we would get by losing both 4s and 3d electrons, toward the end only 2+ is observed, the explanation is that as the effective charge increases thus holding the d electrons tighter.
Reducing ability, decreases from left to right
See common oxidation states on Next slide
The maximum oxidation state for each transition element going across the row is what we would get by losing both 4s and 3d electrons, toward the end only 2+ is observed, the explanation is that as the effective charge increases thus holding the d electrons tighter.
Reducing ability, decreases from left to right
Transition Metal Oxidations #’s
Transition Metal Oxidations #’s
Sc V Ti CrMn
Fe Co Ni Cu Zn
3 2 2 2 2 2 2 2 1 2
3 3 3 3 3 3 3 2
4 4 4 3
4 5
5 6 6 6
7
Ionization Energies Ionization Energies
Red dot- First ionization energy
(removing 4s e)
Blue dot-third ionization energy removing 3d electron, closer to nucleus, thus more tightly held
First-row Transition Metals
First-row Transition Metals
Scandium Rare element most always +3 oxidation
state, ie ScCl3, Sc2O3
Chemistry of scandium resembles the lanthanides
Colorless compounds Diamagnetic Color and magnetic properties are due to d
electron, Sc has no d electrons
Scandium Rare element most always +3 oxidation
state, ie ScCl3, Sc2O3
Chemistry of scandium resembles the lanthanides
Colorless compounds Diamagnetic Color and magnetic properties are due to d
electron, Sc has no d electrons
First-row Transition MetalsFirst-row Transition Metals
Titanium Found in the earths crust (0.6%) Low density and high strength Fairly inert, and is used in pipes TiO2 is a very common white pigment Common oxidation state is +4
Titanium Found in the earths crust (0.6%) Low density and high strength Fairly inert, and is used in pipes TiO2 is a very common white pigment Common oxidation state is +4
First-row Transition Metals
First-row Transition Metals
Vanadium Found in the earth’s crust about 0.02% Common oxidation state is +5 Since vanadium contains d electrons solutions
are coloredVO2
+ is yellow with V in the +5 oxidation stateVO2+ is blue with V in the +4 oxidation stateV3+ is blue-green with V in +3 oxidation stateV2+ is violet with V in +2 oxidation state
Vanadium Found in the earth’s crust about 0.02% Common oxidation state is +5 Since vanadium contains d electrons solutions
are coloredVO2
+ is yellow with V in the +5 oxidation stateVO2+ is blue with V in the +4 oxidation stateV3+ is blue-green with V in +3 oxidation stateV2+ is violet with V in +2 oxidation state
First-row Transition Metals
First-row Transition Metals
Chromium– Rare, but important industrial chemical– Chromium oxide is colorless, tuff, and holds to
the metal strongly, almost invisible– Chromium compounds in solution are also
colored since they contain d electrons– Common oxidation states are +2, +3 and +6– Chromium VI is an excellent oxidizing agent!
Why?• Strength increases as acidity increases• Chromerge very good glassware cleaning agent
– What would we predict for Cr metal?– Cr6+ in the form of dichromate ion usually
reduces to the +3 state
Chromium– Rare, but important industrial chemical– Chromium oxide is colorless, tuff, and holds to
the metal strongly, almost invisible– Chromium compounds in solution are also
colored since they contain d electrons– Common oxidation states are +2, +3 and +6– Chromium VI is an excellent oxidizing agent!
Why?• Strength increases as acidity increases• Chromerge very good glassware cleaning agent
– What would we predict for Cr metal?– Cr6+ in the form of dichromate ion usually
reduces to the +3 state
First-row Transition Metals
First-row Transition Metals• Iron
– Is the most abundant heavy metal (4.7%) in earth’s crust, Why?
– Common oxidation states +2 and +3– Iron solutions are colored since they contain
d electrons
• Cobalt– Relatively rare– Hard bluish-white metal– Common oxidation states are +2 and +3– Oxidation states +1 and +4 are also known• Typical color is rose color
• Iron– Is the most abundant heavy metal (4.7%) in
earth’s crust, Why?– Common oxidation states +2 and +3– Iron solutions are colored since they contain
d electrons
• Cobalt– Relatively rare– Hard bluish-white metal– Common oxidation states are +2 and +3– Oxidation states +1 and +4 are also known• Typical color is rose color
First-row Transition Metals
First-row Transition Metals
Nickel Most always the +2 oxidation state Sometimes +3 oxidation state Emerald green colored solutions
Nickel Most always the +2 oxidation state Sometimes +3 oxidation state Emerald green colored solutions
First-row Transition Metals
First-row Transition Metals• Copper
– Quite common, as sulfides, arsenides, chlorides and carbonates
– Great electrical conductor second only to silver– Widely used in plumbing– Found in bronze and brass– Not highly reactive will not reduce H+
– Slowly oxides in air, producing a green oxide– Common oxidation state +2, +1 is also known– Aqueous solution are bright Royal blue– Quite toxic, used to kill bacteria– Paint often contains copper so algae do not
grow on the paint
• Copper– Quite common, as sulfides, arsenides, chlorides
and carbonates– Great electrical conductor second only to silver– Widely used in plumbing– Found in bronze and brass– Not highly reactive will not reduce H+
– Slowly oxides in air, producing a green oxide– Common oxidation state +2, +1 is also known– Aqueous solution are bright Royal blue– Quite toxic, used to kill bacteria– Paint often contains copper so algae do not
grow on the paint
First-row Transition Metals
First-row Transition Metals
Zinc Quite common in earths crust, usually as ZnS Great reducing agent, quite reactive Oxidation state of +2 Used to galvanize steel
Zinc Quite common in earths crust, usually as ZnS Great reducing agent, quite reactive Oxidation state of +2 Used to galvanize steel
Coordination compounds
Coordination compounds
Transition metals form coordination compounds
Transition metals contain a complex ion attached to ligands via coordinate covalent bonds
Coordination compounds are usually colored and paramagnetic
Transition metals form coordination compounds
Transition metals contain a complex ion attached to ligands via coordinate covalent bonds
Coordination compounds are usually colored and paramagnetic
Coordination compoundsCoordination compounds Complex ions, usually inside [ ]
Transition coordinately bonded to Lewis bases, the metal is acting as a Lewis acid
Example [CoCl(NH3)5]2+ this cation can combine with anions to balance the charge, thus forming a salt
Ligands are the groups of atoms bonded with a coordinate covalent bond to a transition metal, or a transition metal ion.
Complex ions, usually inside [ ] Transition coordinately bonded to
Lewis bases, the metal is acting as a Lewis acid
Example [CoCl(NH3)5]2+ this cation can combine with anions to balance the charge, thus forming a salt
Ligands are the groups of atoms bonded with a coordinate covalent bond to a transition metal, or a transition metal ion.
Coordinate Covalent Bonding
Coordinate Covalent Bonding
Coordinate Covalent Bonding
Coordinate Covalent Bonding
Coordination compoundsCoordination compounds Alfred Werner was the father of
coordination chemistry Alfred Werner called the salt formation
the primary valence The secondary valence is the formation
of the complex ion itself The compound above has a secondary
valence of 6, since it combines with 6 ligands
The primary valence is +2 since that is what needs to be neutralized with anions.
Now days the secondary valence is called the coordination number and the primary valence is called the oxidation state
Alfred Werner was the father of coordination chemistry
Alfred Werner called the salt formation the primary valence
The secondary valence is the formation of the complex ion itself
The compound above has a secondary valence of 6, since it combines with 6 ligands
The primary valence is +2 since that is what needs to be neutralized with anions.
Now days the secondary valence is called the coordination number and the primary valence is called the oxidation state
Aqueous Solutions of Metal Ions
Aqueous Solutions of Metal Ions
Coordination CompoundsCoordination Compounds The number of coordinate covalent
bonds formed by the metal ion and the ligands
Variance of 2-8, with 6 being most common.
Geometrical Shape Ligands = 2, then linear
Rare for most metals Common for d-10 systems (Cu+, Ag+, Au+, Hg2+)
Ligands = 3, Trigonal planar Rare for most metals Is known for d-10 systems (example HgI3
‑)
The number of coordinate covalent bonds formed by the metal ion and the ligands
Variance of 2-8, with 6 being most common.
Geometrical Shape Ligands = 2, then linear
Rare for most metals Common for d-10 systems (Cu+, Ag+, Au+, Hg2+)
Ligands = 3, Trigonal planar Rare for most metals Is known for d-10 systems (example HgI3
‑)
Coordination CompoundsCoordination Compounds• Geometrical Shape
Ligands = 4, then tetrahedral, or square planar Tetrahedral structure is observed for
nontransition metals, BeF42- and d-10 inons
such as ZnCl42-, FeCl4-, FeCl42-
Square planar is found with second and third row transition metals with d-8 Rh+, Pd2+
-Ligands = 5 trigonal bipyramid square pyramidal
• Geometrical Shape Ligands = 4, then tetrahedral, or square planar Tetrahedral structure is observed for
nontransition metals, BeF42- and d-10 inons
such as ZnCl42-, FeCl4-, FeCl42-
Square planar is found with second and third row transition metals with d-8 Rh+, Pd2+
-Ligands = 5 trigonal bipyramid square pyramidal
Coordination compoundsCoordination compounds• Geometrical Shape
− Ligands = 6, then octahedral and prismatic (rare)
− Ligands = 7 Relatively uncommon, pentagonalSecond and third row transition metals,
lanthanides , and actinides− Lignads = 8, relatively common for larger
metal ions, common geometry antiprism and dodecahedron
− Lignads = 9 larger metal ions, geometry tricapped trigonal prism [Nd(H2O)9]3+
The Ligand Arrangements for Coordination Numbers 2, 4, and 6
The Ligand Arrangements for Coordination Numbers 2, 4, and 6
LigandsLigands Atoms attached to a transition metal via
coordinate covalent bonds They are Lewis bases, since they donate
a pair of electrons to the transition metal. Ligands are classified relative to how
many attachments to the metal Monodentate forms one bond to a transition
metal Lignads forming more than bond are called
chelating ligands, or chelates
Atoms attached to a transition metal via coordinate covalent bonds
They are Lewis bases, since they donate a pair of electrons to the transition metal.
Ligands are classified relative to how many attachments to the metal Monodentate forms one bond to a transition
metal Lignads forming more than bond are called
chelating ligands, or chelates
LigandsLigands Ligands are classified relative to how
many attachments to the metal Bidentate, a chelating agent, forms two
bonds, examples:OxalateEthylenediamine
Polydentate forms more than two bonds.DiethylenetriamineEthylenediaminetetraacetic acid
Ligands are classified relative to how many attachments to the metal Bidentate, a chelating agent, forms two
bonds, examples:OxalateEthylenediamine
Polydentate forms more than two bonds.DiethylenetriamineEthylenediaminetetraacetic acid
LigandsLigands EDTA is used to remove lead from
animals More complicated ligands are found in
biological compounds EDTA is used as a preservative to tie up
substances that could catalyze decomposition of food products
EDTA is used to remove lead from animals
More complicated ligands are found in biological compounds
EDTA is used as a preservative to tie up substances that could catalyze decomposition of food products
EthylenediamineEthylenediamine
Ethylenediamminetetracidic acid
Coordination of EDTA with a 2+ Metal Ion
Coordination of EDTA with a 2+ Metal Ion
NomenclatureNomenclature Cationic species named before anionic species Within a complex, the ligands are named first in
alphabetical order followed by the metal atom the names of anionic lignads end in the suffix -o-
chloride ----->chloro cyanide ----->cyano oxide ----->oxo Hydroxide -->hydroxo Oxalate------>oxalato Sulfate ------>Sulfato Nitrate ------>Nitrato
Cationic species named before anionic species Within a complex, the ligands are named first in
alphabetical order followed by the metal atom the names of anionic lignads end in the suffix -o-
chloride ----->chloro cyanide ----->cyano oxide ----->oxo Hydroxide -->hydroxo Oxalate------>oxalato Sulfate ------>Sulfato Nitrate ------>Nitrato
NomenclatureNomenclature lignads whose names end in -ite or ate
become -ito and ato respectively carbonate ----> carbonato oxalate-----> oxalato thiosulfate ----> thiosulfato Sulfite -----> sulfito
neutral lignads are given the same names as the neutral molecule exceptions, ammonia (ammine), water
(aqua), carbon monoxide (Carbonyl), and NO (nitrosyl)
lignads whose names end in -ite or ate become -ito and ato respectively carbonate ----> carbonato oxalate-----> oxalato thiosulfate ----> thiosulfato Sulfite -----> sulfito
neutral lignads are given the same names as the neutral molecule exceptions, ammonia (ammine), water
(aqua), carbon monoxide (Carbonyl), and NO (nitrosyl)
NomenclatureNomenclature When there is more than one of a particular
ligand, number is specified by di, tri, tetra, penta, hexa, and so forth. when confusion might result, the prefixes bis, tris and tetrakis are employed e.g. bis(ethylenediaminne) negative (anionic) complex ions always end
in the suffix -atealuminum -----> aluminate chromium -----> chromatemanganese ------> manganatecoblat ------> cobaltate
For some metals the -ate is appended to the Latin stem always appears with
When there is more than one of a particular ligand, number is specified by di, tri, tetra, penta, hexa, and so forth. when confusion might result, the prefixes bis, tris and tetrakis are employed e.g. bis(ethylenediaminne) negative (anionic) complex ions always end
in the suffix -atealuminum -----> aluminate chromium -----> chromatemanganese ------> manganatecoblat ------> cobaltate
For some metals the -ate is appended to the Latin stem always appears with
NomenclatureNomenclature the common English name for the element
iron ----> ferr ------> ferrate copper ---> cupra -----> cuprate lead ----> plumb -----> plumbate silver ---> argent ----> argentate gold ---> aur ----> aurate tin ----> stann -----> stannate
the oxidation number of the metal in the complex is written in roman numerals within parentheses following the name of the metal
the common English name for the element iron ----> ferr ------> ferrate copper ---> cupra -----> cuprate lead ----> plumb -----> plumbate silver ---> argent ----> argentate gold ---> aur ----> aurate tin ----> stann -----> stannate
the oxidation number of the metal in the complex is written in roman numerals within parentheses following the name of the metal
NomenclatureNomenclature Formula writing
Metal is first, followed by anions, then neutral molecules
If two or more anions or neutral molecules are present, then use alphabetical order.
Nomenclature Examples tetracyanonickelate(II) ion tetramminedichlorocobalt(III) ionsodium hexanitratochromate(III)diamminesilver(I) ion
Formula writing Metal is first, followed by anions, then neutral
molecules If two or more anions or neutral molecules
are present, then use alphabetical order. Nomenclature Examples
tetracyanonickelate(II) ion tetramminedichlorocobalt(III) ionsodium hexanitratochromate(III)diamminesilver(I) ion
NomenclatureNomenclature Formula writing
Metal is first, followed by anions, then neutral molecules
If two or more anions or neutral molecules are present, then use alphabetical order.
Nomenclature Examples tetracyanonickelate(II) ion [Ni(CN)4]2-
tetramminedichlorocobalt(III) ion sodium hexanitratochromate(III) diamminesilver(I) ion
Formula writing Metal is first, followed by anions, then neutral
molecules If two or more anions or neutral molecules
are present, then use alphabetical order. Nomenclature Examples
tetracyanonickelate(II) ion [Ni(CN)4]2-
tetramminedichlorocobalt(III) ion sodium hexanitratochromate(III) diamminesilver(I) ion
NomenclatureNomenclature Formula writing
Metal is first, followed by anions, then neutral molecules
If two or more anions or neutral molecules are present, then use alphabetical order.
Nomenclature Examples tetracyanonickelate(II) ion [Ni(CN)4]2-
tetramminedichlorocobalt(III) ion [CoCl2(NH3)4]+
sodium hexanitratochromate(III) diamminesilver(I) ion
Formula writing Metal is first, followed by anions, then neutral
molecules If two or more anions or neutral molecules
are present, then use alphabetical order. Nomenclature Examples
tetracyanonickelate(II) ion [Ni(CN)4]2-
tetramminedichlorocobalt(III) ion [CoCl2(NH3)4]+
sodium hexanitratochromate(III) diamminesilver(I) ion
NomenclatureNomenclature Formula writing
Metal is first, followed by anions, then neutral molecules
If two or more anions or neutral molecules are present, then use alphabetical order.
Nomenclature Examples tetracyanonickelate(II) ion [Ni(CN)4]2-
tetramminedichlorocobalt(III) ion [Co(NH3)4Cl2]+
sodium hexanitratochromate(III) Na3[Cr(NO3)6] diamminesilver(I) ion
Formula writing Metal is first, followed by anions, then neutral
molecules If two or more anions or neutral molecules
are present, then use alphabetical order. Nomenclature Examples
tetracyanonickelate(II) ion [Ni(CN)4]2-
tetramminedichlorocobalt(III) ion [Co(NH3)4Cl2]+
sodium hexanitratochromate(III) Na3[Cr(NO3)6] diamminesilver(I) ion
NomenclatureNomenclature Formula writing
Metal is first, followed by anions, then neutral molecules
If two or more anions or neutral molecules are present, then use alphabetical order.
Nomenclature Examples tetracyanonickelate(II) ion [Ni(CN)4]2-
tetramminedichlorocobalt(III) ion [CoCl2 NH3)4]+
sodium hexanitratochromate(III) Na3[Cr(NO3)6]
diamminesilver(I) ion [Ag(NH3)2]+
Formula writing Metal is first, followed by anions, then neutral
molecules If two or more anions or neutral molecules
are present, then use alphabetical order. Nomenclature Examples
tetracyanonickelate(II) ion [Ni(CN)4]2-
tetramminedichlorocobalt(III) ion [CoCl2 NH3)4]+
sodium hexanitratochromate(III) Na3[Cr(NO3)6]
diamminesilver(I) ion [Ag(NH3)2]+
NomenclatureNomenclature Formula writing
Metal is first, followed by anions, then neutral molecules
If two or more anions or neutral molecules are present, then use alphabetical order.
Nomenclature Examples tetracyanonickelate(II) ion [Ni(CN)4]2-
tetramminedichlorocobalt(III) ion [CoCl2(NH3)4]+
sodium hexanitratochromate(III) Na3[Cr(NO3)6]
diamminesilver(I) ion [Ag(NH3)2]+
Formula writing Metal is first, followed by anions, then neutral
molecules If two or more anions or neutral molecules
are present, then use alphabetical order. Nomenclature Examples
tetracyanonickelate(II) ion [Ni(CN)4]2-
tetramminedichlorocobalt(III) ion [CoCl2(NH3)4]+
sodium hexanitratochromate(III) Na3[Cr(NO3)6]
diamminesilver(I) ion [Ag(NH3)2]+
NomenclatureNomenclatureName the following:
[Ni(H2O)6]Cl2 hexaaquanickel(II) chloride
[Cr(en)3](ClO3)3
K4[Mn(CN)6]
K[PtCl5 (NH3)]
[Cu(en)(NH3)2][Co(en)Cl4]
[Pt(en)2Br2](ClO4)2
Name the following: [Ni(H2O)6]Cl2 hexaaquanickel(II)
chloride [Cr(en)3](ClO3)3
K4[Mn(CN)6]
K[PtCl5 (NH3)]
[Cu(en)(NH3)2][Co(en)Cl4]
[Pt(en)2Br2](ClO4)2
NomenclatureNomenclatureName the following:
[Ni(H2O)6]Cl2 hexaaquanickel(II) chloride
[Cr(en)3](ClO3)3
tris(ethylenediamene)chromium(III) chlorate
K4[Mn(CN)6]
K[PtCl5(NH3)]
[Cu(en)(NH3)2][Co(en)Cl4]
[Pt(en)2Br2](ClO4)2
Name the following: [Ni(H2O)6]Cl2 hexaaquanickel(II)
chloride [Cr(en)3](ClO3)3
tris(ethylenediamene)chromium(III) chlorate
K4[Mn(CN)6]
K[PtCl5(NH3)]
[Cu(en)(NH3)2][Co(en)Cl4]
[Pt(en)2Br2](ClO4)2
NomenclatureNomenclatureName the following:
[Ni(H2O)6]Cl2 hexaaquanickel(II) chloride
[Cr(en)3](ClO3)3
trisethylenediamenechromium(III) chlorate
K4[Mn(CN)6] Potassium hexacyanomanganate(IV)
K[PtCl5(NH3)]
[Cu(en)(NH3)2][Co(en)Cl4]
[Pt(en)2Br2](ClO4)2
Name the following: [Ni(H2O)6]Cl2 hexaaquanickel(II) chloride
[Cr(en)3](ClO3)3
trisethylenediamenechromium(III) chlorate
K4[Mn(CN)6] Potassium hexacyanomanganate(IV)
K[PtCl5(NH3)]
[Cu(en)(NH3)2][Co(en)Cl4]
[Pt(en)2Br2](ClO4)2
NomenclatureNomenclatureName the following:[Ni(H2O)6]Cl2 hexaaquanickel(II) chloride
[Cr(en)3](ClO3)3
trisethylenediamenechromium(III) chlorate
K4[Mn(CN)6] Potassium hexacyanomanganate(IV)
K[PtCl5(NH3)] Potassium monoaminepentachloroplatinate(IV)
[Cu(en)(NH3)2][Co(en)Cl4]
[PtBr2(en)2](ClO4)2
Name the following:[Ni(H2O)6]Cl2 hexaaquanickel(II) chloride
[Cr(en)3](ClO3)3
trisethylenediamenechromium(III) chlorate
K4[Mn(CN)6] Potassium hexacyanomanganate(IV)
K[PtCl5(NH3)] Potassium monoaminepentachloroplatinate(IV)
[Cu(en)(NH3)2][Co(en)Cl4]
[PtBr2(en)2](ClO4)2
NomenclatureNomenclatureName the following:[Ni(H2O)6]Cl2 hexaaquanickel(II) chloride
[Cr(en)3](ClO3)3 trisethylenediamenechromium(III) chlorate
K4[Mn(CN)6] Potassium hexacyanomanganate(IV)
K[PtCl5(NH3)] Potassium triaminpentachloroplatinate(IV)
[Cu(en)(NH3)2][Co(en)Cl4] ethylenediaminediaminecopper(II) tetrachloroethylenediaminecobaltate(II)
[Pt(Br2en)2](ClO4)2
Name the following:[Ni(H2O)6]Cl2 hexaaquanickel(II) chloride
[Cr(en)3](ClO3)3 trisethylenediamenechromium(III) chlorate
K4[Mn(CN)6] Potassium hexacyanomanganate(IV)
K[PtCl5(NH3)] Potassium triaminpentachloroplatinate(IV)
[Cu(en)(NH3)2][Co(en)Cl4] ethylenediaminediaminecopper(II) tetrachloroethylenediaminecobaltate(II)
[Pt(Br2en)2](ClO4)2
NomenclatureNomenclatureName the following:[Ni(H2O)6]Cl2 hexaaquanickel(II) chloride
[Cr(en)3](ClO3)3 tris(ethylenediamene)chromium(III) chlorate
K4[Mn(CN)6] Potassium hexacyanomanganate(IV)
K[PtCl5 (NH3)] Potassium monoaminpentachloroplatinate(IV)
[Cu(en)(NH3)2][Co(en)Cl4] ethylenediaminediamincopper(II) tetrachloroethylenediaminecobaltate(II)
[Pt(en)2Br2](ClO4)2
bis(ethylenediamine)dibromoplatinum(IV) perchlorate
Name the following:[Ni(H2O)6]Cl2 hexaaquanickel(II) chloride
[Cr(en)3](ClO3)3 tris(ethylenediamene)chromium(III) chlorate
K4[Mn(CN)6] Potassium hexacyanomanganate(IV)
K[PtCl5 (NH3)] Potassium monoaminpentachloroplatinate(IV)
[Cu(en)(NH3)2][Co(en)Cl4] ethylenediaminediamincopper(II) tetrachloroethylenediaminecobaltate(II)
[Pt(en)2Br2](ClO4)2
bis(ethylenediamine)dibromoplatinum(IV) perchlorate
Some Classes of IsomersSome Classes of Isomers
Coordination IsomersCoordination Isomers Structural (constitutional) isomers
Definition- Different compounds of the same formula.
Types of structural (constitutional) isomers Ionization isomerism
[Cr(NH3)SO4]Cl ppts AgCl when silver nitrate is added [Cr(NH3Cl)]SO4 ppts barium sulfate when barium is added
Hydrate isomers differ in the placement of water Coordination isomers differ in the placement of
ligands between the metal atoms [CuBr4][PtCl4] or [CuCl4][PtBr4]
Structural (constitutional) isomers Definition- Different compounds of the same
formula. Types of structural (constitutional) isomers
Ionization isomerism [Cr(NH3)SO4]Cl ppts AgCl when silver nitrate is added
[Cr(NH3Cl)]SO4 ppts barium sulfate when barium is added
Hydrate isomers differ in the placement of water Coordination isomers differ in the placement of
ligands between the metal atoms [CuBr4][PtCl4] or [CuCl4][PtBr4]
Coordination IsomersCoordination Isomers Types of structural (constitutional) isomers
Linkage isomers differ by the atom that is coordinated to the metal O-N-O-M O2N-M, bond to oxygen, or bond to nitrogen
Stereoisomerism (octahedral use models) Definition, Same formula, same attachment of
atoms, but atoms are in different volumes of space geometrical isomers (cis and trans)
cis-[Co(NH3)4Cl2]+ chlorides on same side trans- chlorides on the opposite side
Types of structural (constitutional) isomers Linkage isomers differ by the atom that is
coordinated to the metal O-N-O-M O2N-M, bond to oxygen, or bond to nitrogen
Stereoisomerism (octahedral use models) Definition, Same formula, same attachment of
atoms, but atoms are in different volumes of space geometrical isomers (cis and trans)
cis-[Co(NH3)4Cl2]+ chlorides on same side trans- chlorides on the opposite side
As a Ligand, NO2
- can Bond to a Metal Ion (a) Through a Lone Pair on the Nitrogen Atom or (b) Through a Lone Pair on One of the Oxygen Atoms
As a Ligand, NO2
- can Bond to a Metal Ion (a) Through a Lone Pair on the Nitrogen Atom or (b) Through a Lone Pair on One of the Oxygen Atoms
(a) The cis Isomer of Pt(NH3)2Cl2
(b) The trans Isomer of Pt(NH3)2Cl
2
(a) The cis Isomer of Pt(NH3)2Cl2
(b) The trans Isomer of Pt(NH3)2Cl
2
The Compound [Co(NH3)4Cl2]Cl has cis and trans Isomers
The Compound [Co(NH3)4Cl2]Cl has cis and trans Isomers
Optical IsomersOptical IsomersOptical isomers(nonsuperimposable mirror images)
Chiral molecule-nonsuperimposable on it’s mirror image
Enantiomers-a pair of nonsuperimposable mirror images
Ploarimeter-an instrument that measures the rotation of polarized light by an optically active compound
Dextrorotatory-rotation of polarized light clockwise
Levorotatory-rotation of polarized light counterclockwise
Racemates- a 50/50 mixture of enantiomers (no rotation of polarized light)
Optical isomers(nonsuperimposable mirror images)
Chiral molecule-nonsuperimposable on it’s mirror image
Enantiomers-a pair of nonsuperimposable mirror images
Ploarimeter-an instrument that measures the rotation of polarized light by an optically active compound
Dextrorotatory-rotation of polarized light clockwise
Levorotatory-rotation of polarized light counterclockwise
Racemates- a 50/50 mixture of enantiomers (no rotation of polarized light)
A human hand exhibits a nonsuperimposable mirror image. Note that the mirror image of the right hand (while identical to the left hand) cannot be turned in any way to make it identical to (superimposable on) the actual right hand.
A human hand exhibits a nonsuperimposable mirror image. Note that the mirror image of the right hand (while identical to the left hand) cannot be turned in any way to make it identical to (superimposable on) the actual right hand.
Optical Isomers
Isomers I and II of CO(en)33+ are Mirror Images
that Cannot be SuperimposedIsomers I and II of CO(en)3
3+ are Mirror Images that Cannot be Superimposed
Optical Isomers
(a) Superimposable. (b) Not Superimposable
(a) Superimposable. (b) Not Superimposable
Optical Isomers
Polarized LightPolarized Light
Rotating the Plane of Polarization of Light Rotating the Plane of Polarization of Light
Polarized Light
Valence Bond ModelValence Bond Model
Valence bond (VB) approach (Localized Model) relative to octahedral systems
Overlay of the atomic orbitals of the metal and the ligands
Since the ligands normally do not possess single electrons, then a pair of electrons from the ligand, must overlap with the empty orbitals of the metal
Valence bond (VB) approach (Localized Model) relative to octahedral systems
Overlay of the atomic orbitals of the metal and the ligands
Since the ligands normally do not possess single electrons, then a pair of electrons from the ligand, must overlap with the empty orbitals of the metal
Valence Bond ModelValence Bond Model
Consider for example the blue-violet [Cr(H2O)6]3+ complex
This is a 3d3 system, thus the 6 electron pairs from the water will occupy the d2sp3 hybrid (note the 4s and 4p orbitals are used here)
The 4d orbitals are not used in this case, since the 3d orbitals are lower in energy, and the bonds formed are stronger
The orbital notation shows three single electrons, verified by Gouy Balance measurements.
Consider for example the blue-violet [Cr(H2O)6]3+ complex
This is a 3d3 system, thus the 6 electron pairs from the water will occupy the d2sp3 hybrid (note the 4s and 4p orbitals are used here)
The 4d orbitals are not used in this case, since the 3d orbitals are lower in energy, and the bonds formed are stronger
The orbital notation shows three single electrons, verified by Gouy Balance measurements.
4s 4p3d
Gouy BalanceGouy Balance
Valence Bond ModelValence Bond ModelConsider next the [Ni(H2O)6]2+
This is a d8 system, there are no empty 3d orbitals
The 6 ligands, then will occupy the 4th energy shell sp3d2
The orbital notation shows two unpaired electrons, verified by experiment
Consider next the [Ni(H2O)6]2+
This is a d8 system, there are no empty 3d orbitals
The 6 ligands, then will occupy the 4th energy shell sp3d2
The orbital notation shows two unpaired electrons, verified by experiment
4s 4p3d 4d
Valence Bond ModelValence Bond Model
When 3d orbitals are employed, the system is referred to as an inner orbital complex; where if the 4d orbitals are used, then the system is referred to as an outer orbital complex.
In the two previous examples there was no choice where the electrons are placed.
When 3d orbitals are employed, the system is referred to as an inner orbital complex; where if the 4d orbitals are used, then the system is referred to as an outer orbital complex.
In the two previous examples there was no choice where the electrons are placed.
Coordination Compound Bonding
Coordination Compound Bonding
Co3+ is an ion that can show either inner orbital, or an outer orbital complexes
Co3+ is d 6 system Pairing up the 6 electrons, will
produce an inner orbital d2sp3, which is diamagnetic
If the d electrons are not paired, then an outer orbital sp3d2 complex is formed, with 4 unpaired electrons and paramagnetic
Co3+ is an ion that can show either inner orbital, or an outer orbital complexes
Co3+ is d 6 system Pairing up the 6 electrons, will
produce an inner orbital d2sp3, which is diamagnetic
If the d electrons are not paired, then an outer orbital sp3d2 complex is formed, with 4 unpaired electrons and paramagnetic
Valence Bond ModelValence Bond ModelTo pair, or not to pair, that is the question
This question arises for d 4,5,6 systems Failure to pair produces outer orbital
systems Two factors to consider
Stronger bonds are formed from 3d orbitals, than 4d orbitals
Pairing means putting two electrons in the same orbital. A higher energy system for sure (electron repulsion), but the outer orbital system does not require pairing electrons
To pair, or not to pair, that is the question This question arises for d 4,5,6 systems Failure to pair produces outer orbital
systems Two factors to consider
Stronger bonds are formed from 3d orbitals, than 4d orbitals
Pairing means putting two electrons in the same orbital. A higher energy system for sure (electron repulsion), but the outer orbital system does not require pairing electrons
Valence Bond ModelValence Bond Model
If the formation of bonds releases more energy than the pairing energy, then the inner orbital complex is preferred; if not, then the outer orbital complex is favored
Most first row transition elements when combined with ligands tend to favor inner orbital complexes for d4 or d6 systems, with the exception of the ligands H2O and F-, which usually prefer outer orbital complexes
If the formation of bonds releases more energy than the pairing energy, then the inner orbital complex is preferred; if not, then the outer orbital complex is favored
Most first row transition elements when combined with ligands tend to favor inner orbital complexes for d4 or d6 systems, with the exception of the ligands H2O and F-, which usually prefer outer orbital complexes
Valence Bond ModelValence Bond Model
The d-5 system produced the half filled system (chromium), which is weird.
It is hard to disturb this stability, thus paring usually does not happen, thus these systems prefer outer orbital complexes with most complexes, but CN- is an exception
The d-5 system produced the half filled system (chromium), which is weird.
It is hard to disturb this stability, thus paring usually does not happen, thus these systems prefer outer orbital complexes with most complexes, but CN- is an exception
Valence Bond ModelValence Bond ModelValence bond approach and other geometries
Consider [Ni(CN)4]2- which is square planar and diamagnetic
Here Ni2+ is a d-8 system Here pairing will create an empty d orbital, thus
allowing the dsp2 hybrid orbital system to form Cyanide, is a strong ligand, as it was in the
octahedral system
The [CoCl4]2- complex forms the tetrahedral geometry
This is a d-7 system Tetrahedral here and sp3
Valence bond approach and other geometries Consider [Ni(CN)4]2- which is square planar
and diamagnetic Here Ni2+ is a d-8 system Here pairing will create an empty d orbital, thus
allowing the dsp2 hybrid orbital system to form Cyanide, is a strong ligand, as it was in the
octahedral system
The [CoCl4]2- complex forms the tetrahedral geometry
This is a d-7 system Tetrahedral here and sp3
Valence Bond ModelValence Bond ModelOne of the most striking physical properties of the coordination compounds is their color, and the valence bond theory does little to explain color.
One of the most striking physical properties of the coordination compounds is their color, and the valence bond theory does little to explain color.
Crystal Field Splitting Theory
Crystal Field Splitting Theory
Crystal field splitting theory (CF) Developed by physics to explain impurities
in crystal lattices Electrostatic bonds no coordinate
covalent bonds Ligands are anions or polar particles
Crystal field splitting theory (CF) Developed by physics to explain impurities
in crystal lattices Electrostatic bonds no coordinate
covalent bonds Ligands are anions or polar particles
Crystal Field Splitting Theory
Crystal Field Splitting Theory Another modified version of molecular
orbital theory Organizes the d orbitals in order of increasing
energy Organization of energy depends on the
geometry of the complex ion Consider the geometry of the d orbitals page
967 As a ligand approaches in an octahedral
complex, the nonbonding electrons will repel electrons found in the dz2 and dx2-y2, thus splitting the potential energy of the 5 d orbitals, this is where the name Crystal Field Splitting theory comes from
Another modified version of molecular orbital theory
Organizes the d orbitals in order of increasing energy
Organization of energy depends on the geometry of the complex ion
Consider the geometry of the d orbitals page 967
As a ligand approaches in an octahedral complex, the nonbonding electrons will repel electrons found in the dz2 and dx2-y2, thus splitting the potential energy of the 5 d orbitals, this is where the name Crystal Field Splitting theory comes from
Crystal Field Splitting Theory
Crystal Field Splitting Theory
Crystal Field Splitting Theory
Crystal Field Splitting Theory
The average energy of the d orbitals is not altered
The energy difference is called Δo where the o means octahedral
The two d orbitals of higher energy are called eg while the three lower energy orbitals are called t2g
The eg increases in energy by 0.6, and the t2g decreases in energy by 0.4, thus total energy change is zero
The average energy of the d orbitals is not altered
The energy difference is called Δo where the o means octahedral
The two d orbitals of higher energy are called eg while the three lower energy orbitals are called t2g
The eg increases in energy by 0.6, and the t2g decreases in energy by 0.4, thus total energy change is zero
Crystal Field SplittingCrystal Field Splitting
CF Energy DiagramCF Energy Diagram
Octahedral and Tetrahedral Splits
Octahedral and Tetrahedral Splits
Some d SystemsSome d Systems
Some d SystemsSome d Systems
Some d SystemsSome d Systems
Some d SystemsSome d Systems
Crystal Field SplittingCrystal Field Splitting
The energy difference is called Δo where the o means octahedral
Referred to as the crystal field splitting Absorption of light corresponds to delta, the
greater the difference the more blue in color light is absorbed, all other colors are reflected
The energy absorbed is related to the wave length
The energy difference is called Δo where the o means octahedral
Referred to as the crystal field splitting Absorption of light corresponds to delta, the
greater the difference the more blue in color light is absorbed, all other colors are reflected
The energy absorbed is related to the wave length
Crystal Field SplittingCrystal Field Splitting Placement of electrons into these
5 psudo-molecular orbitals depends on the magnitude of Δo and the pairing energy P
If Δo < P, then the next electron goes into the eg orbital, creating a high spin case
If Δo > P, then the next electron goes into t2g creating low spin case
Placement of electrons into these 5 psudo-molecular orbitals depends on the magnitude of Δo and the pairing energy P
If Δo < P, then the next electron goes into the eg orbital, creating a high spin case
If Δo > P, then the next electron goes into t2g creating low spin case
Examples With Pairing Energy
Examples With Pairing Energy
Crystal Field SplittingCrystal Field SplittingFactors affecting magnitude of Δo
Charge on metal ion Increasing charge causes radius to decrease,
thus ligands are more strongly attached, thus increasing Δo
The Δo for a tripositive ion is about 50% when compared to a dipositive ion
Principle quantum number With the same charge and same ligands, then
as we travel down a group then Δo increases This effect is due to the larger radius of the
metal ion Repulsive ligand forces are important in
smaller metal ions
Factors affecting magnitude of Δo
Charge on metal ion Increasing charge causes radius to decrease,
thus ligands are more strongly attached, thus increasing Δo
The Δo for a tripositive ion is about 50% when compared to a dipositive ion
Principle quantum number With the same charge and same ligands, then
as we travel down a group then Δo increases This effect is due to the larger radius of the
metal ion Repulsive ligand forces are important in
smaller metal ions
Crystal Field SplittingCrystal Field SplittingNature of the ligands
For ligands of the same group, the Δo decreases as the size of the ligand increases
Smaller more localized charges interact more strongly with the d orbitals of the metal ion.
Small neutral ligands with a localized pair of electrons, i.e. NH3, gives larger than expected Δo, when compared to a spherical ligand such as F-, that has unlocalized electrons
Nature of the ligands For ligands of the same group, the Δo
decreases as the size of the ligand increases
Smaller more localized charges interact more strongly with the d orbitals of the metal ion.
Small neutral ligands with a localized pair of electrons, i.e. NH3, gives larger than expected Δo, when compared to a spherical ligand such as F-, that has unlocalized electrons
Crystal Field SplittingCrystal Field Splitting If the ligands cause a large splitting
(large value of Δ) then the electrons will fill the lower t2g orbital first, thus minimizing the single electrons (strong field case) (low spin)
If the ligands cause a small splitting (low value of Δ) then the electrons will fill the t2g one at a time and then fill the eg orbitals one at a time (Weak field case) (high spin)
If the ligands cause a large splitting (large value of Δ) then the electrons will fill the lower t2g orbital first, thus minimizing the single electrons (strong field case) (low spin)
If the ligands cause a small splitting (low value of Δ) then the electrons will fill the t2g one at a time and then fill the eg orbitals one at a time (Weak field case) (high spin)
Low Spin d-4 SystemLow Spin d-4 System
High Spin d-4 SystemHigh Spin d-4 System
Crystal Field SplittingCrystal Field Splitting Only d 4,5,6,7 have a choice of high
spin, or low spin This model explains magnetic and
color properties of complexes. Color chart or color wheel
Only d 4,5,6,7 have a choice of high spin, or low spin
This model explains magnetic and color properties of complexes.
Color chart or color wheel
Color WheelColor Wheel
Visible SpectrumVisible Spectrum
Crystal Field SplittingCrystal Field Splitting
Magnitude of splitting Magnitude of ΔO depends on the charge of
the central metal, the higher the greater ΔO
For example NH3 is weak field with Co 2+ and strong field with Co 3+
As charge increases the ligands are drawn closer to the metal, thus the closer the greater the splitting
Magnitude of splitting Magnitude of ΔO depends on the charge of
the central metal, the higher the greater ΔO
For example NH3 is weak field with Co 2+ and strong field with Co 3+
As charge increases the ligands are drawn closer to the metal, thus the closer the greater the splitting
Crystal Field SplittingCrystal Field Splitting Depends on polarity, size, etc. I-<Br-<Cl-<acetate<F-<OH-
<oxalate<H2O<SCN-<NH3<en<NO2-
<CN-≈CO Iodine is the smallest splitting
Depends on polarity, size, etc. I-<Br-<Cl-<acetate<F-<OH-
<oxalate<H2O<SCN-<NH3<en<NO2-
<CN-≈CO Iodine is the smallest splitting
Crystal Field SplittingCrystal Field Splitting Cobalt here can have two
possibilities Depends what the ligands are High spin same as outer Low spin same as inner If iodine is used we have high spin
Because delta is not large
Cobalt here can have two possibilities
Depends what the ligands are High spin same as outer Low spin same as inner If iodine is used we have high spin
Because delta is not large
Crystal Field SplittingCrystal Field Splitting Bond formation overcomes small
delta If aqua is used we have the low spin
case All paired Diamagnetic Different colors because delta is different
The possibility of high spin or low spin exists when
D=4,5,6 or 7, Choice between High and Low spin
d 0,1,2,3,8,9,10 High spin only
Bond formation overcomes small delta
If aqua is used we have the low spin case
All paired Diamagnetic Different colors because delta is different
The possibility of high spin or low spin exists when
D=4,5,6 or 7, Choice between High and Low spin
d 0,1,2,3,8,9,10 High spin only
Crystal Field SplittingCrystal Field Splitting Crystal Field Stabilization Energies
If the t2g populated, then stability is increased, since it is lower potential energy
Stabilization can be calculated by multiplying the number of electrons in the t2g orbital by 0.4Δ
If a combination occupied by t2g and eg then subtract 0.4 t2g from 0.6 eg for stabilization energy
Wave numbers Energies obtained by spectroscopic measurements
are oftern given in units of wave numbers (cm-1) Wave number is the reciprocal of the wavelength of
the corresponding electromagnetic radiation expressed in cm
cm-1 = 11.96 j
Crystal Field Stabilization Energies If the t2g populated, then stability is increased, since
it is lower potential energy Stabilization can be calculated by multiplying the
number of electrons in the t2g orbital by 0.4Δ
If a combination occupied by t2g and eg then subtract 0.4 t2g from 0.6 eg for stabilization energy
Wave numbers Energies obtained by spectroscopic measurements
are oftern given in units of wave numbers (cm-1) Wave number is the reciprocal of the wavelength of
the corresponding electromagnetic radiation expressed in cm
cm-1 = 11.96 j
Color and the Colors of ComplexesColor and the Colors of Complexes
Two types of mixing colors Additive, occurs when colored lights
are superimposed on each other Subtractive, occurs when colored
paints are mixed with each other
Two types of mixing colors Additive, occurs when colored lights
are superimposed on each other Subtractive, occurs when colored
paints are mixed with each other
Crystal Field Splitting
Additive Mixing (light beams)Additive Mixing (light beams) For additive mixing a primary
color is defined as any three colors that produce white light Examples:
R + G + B = W
Secondary colors are those that are produced by combining two primary colors Examples:
R + G = YR + B = M
For additive mixing a primary color is defined as any three colors that produce white light Examples:
R + G + B = W
Secondary colors are those that are produced by combining two primary colors Examples:
R + G = YR + B = M
Crystal Field Splitting
Additive and Subtractive MixingAdditive and Subtractive Mixing
Crystal Field Splitting
Complex SolutionsComplex Solutions
Subtractive MixingSubtractive Mixing Some wave lengths of white light are
removed from absorption (promoting electrons to higher levels)
The reflected light, does not contained the absorbed colors, thus has a color due to the absence of another color.
Here primary colors are M,Y, and BG; while secondary colors are G, B, and R.
If a material absorbs all three primary colors, then there in no light left to be reflected, thus black.
Some wave lengths of white light are removed from absorption (promoting electrons to higher levels)
The reflected light, does not contained the absorbed colors, thus has a color due to the absence of another color.
Here primary colors are M,Y, and BG; while secondary colors are G, B, and R.
If a material absorbs all three primary colors, then there in no light left to be reflected, thus black.
Subtractive MixingSubtractive Mixing
If a material absorbs one color, primary or secondary, the reflected or transmitted color is the complimentary color.
Thus a magenta shirt has that color because the dye it contains strongly absorbs green light and reflects the magenta, the compliment of green (see color wheel)
If a material absorbs one color, primary or secondary, the reflected or transmitted color is the complimentary color.
Thus a magenta shirt has that color because the dye it contains strongly absorbs green light and reflects the magenta, the compliment of green (see color wheel)
Color WheelColor Wheel
Colored SolutionsColored Solutions
Colored solutions absorb photons of white light to promote electrons to higher energy levels.
White light, minus the absorbed color, is no longer white, but appears as the compliment of the color that was absorbed
Ions having noble gas configurations do not have energy absorptions in the visible range, thus they appear colorless; likd NaCl (aq)
Colored solutions absorb photons of white light to promote electrons to higher energy levels.
White light, minus the absorbed color, is no longer white, but appears as the compliment of the color that was absorbed
Ions having noble gas configurations do not have energy absorptions in the visible range, thus they appear colorless; likd NaCl (aq)
Colored SolutionsColored Solutions Crystal field splitting deals with d-electrons
and not Noble gas structures. The do absorb in the visible spectrum and
we see the color of the light that is complimentary to the color absorbed
A solution containing [Cu(H2O)4]2+ absorbs most strongly in the yellow region of the spectrum (about 580 nm)
The wavelength of the transmitted light is violet
Crystal field splitting deals with d-electrons and not Noble gas structures.
The do absorb in the visible spectrum and we see the color of the light that is complimentary to the color absorbed
A solution containing [Cu(H2O)4]2+ absorbs most strongly in the yellow region of the spectrum (about 580 nm)
The wavelength of the transmitted light is violet
Acidity of Coordination Compounds
Acidity of Coordination Compounds
Water molecules coordinately bonded to a metal ion can lose a proton, thus causing the hydrate to act as an acid
Water molecules coordinately bonded to a metal ion can lose a proton, thus causing the hydrate to act as an acid
Acidic HydratesAcidic HydratesWater molecules coordinately bonded to a metal ion can lose a proton, thus causing the hydrate to act as an acid
Water molecules coordinately bonded to a metal ion can lose a proton, thus causing the hydrate to act as an acid
Cr(H2O)63+
Cr(H2O)5(OH)2+ + H+ ka = 1 X 10-4
Acidic HydratesAcidic HydratesWater molecules coordinately bonded to a metal ion can lose a proton, thus causing the hydrate to act as an acid
Water molecules coordinately bonded to a metal ion can lose a proton, thus causing the hydrate to act as an acid
Cr(H2O)63+
Cr(H2O)5(OH)2+ + H+ ka = 1 X 10-4
Ka =[Cr(H2O)5(OH)2+][H+]
[Cr(H2O)63+]
The hydroxide ion is bonded to the transition metal cation. The greater the charge of the metal ion and the smaller it is produces a stronger attraction to the hydroxide thus making the complex more stable and more acidic.
Acidic HydratesAcidic HydratesWater molecules coordinately bonded to a metal ion can lose a proton, thus causing the hydrate to act as an acid
Water molecules coordinately bonded to a metal ion can lose a proton, thus causing the hydrate to act as an acid
Cr(H2O)63+
Cr(H2O)5(OH)2+ + H+ ka = 1 X 10-4
Ka =[Cr(H2O)5(OH)2+][H+]
[Cr(H2O)63+]
Calculate the pH of a 1.00 M solution of Cr3+
Ka =(x)(x)1.0-x = 1.00 X 10-4
Acidic HydratesAcidic HydratesWater molecules coordinately bonded to a metal ion can lose a proton, thus causing the hydrate to act as an acid
Water molecules coordinately bonded to a metal ion can lose a proton, thus causing the hydrate to act as an acid
Cr(H2O)63+
Cr(H2O)5(OH)2+ + H+ ka = 1 X 10-4
Ka =[Cr(H2O)5(OH)2+][H+]
[Cr(H2O)63+]
Calculate the pH of a 1.00 M solution of Cr3+
Ka =(x)(x)1.0-x = 1.00 X 10-4
[H+] = 10-4
pH = - log10-
4
pH = 4
Solubility of Ionic Compounds
Solubility of Ionic Compounds
When a precipitate forms the solution is said to be saturatedSaturated solutions can also be formed by adding to much soluteAn equilibrium exists between ions forming solid and the solid dissolving to form ions.From the equilibrium constant we can determine the molar solubility
When a precipitate forms the solution is said to be saturatedSaturated solutions can also be formed by adding to much soluteAn equilibrium exists between ions forming solid and the solid dissolving to form ions.From the equilibrium constant we can determine the molar solubility
Silver Chloride Solubility
Silver Chloride Solubility
Silver chloride is known to be insoluble according to our solubility rules, but some does dissolve.
Silver chloride is known to be insoluble according to our solubility rules, but some does dissolve.
AgCl(s) Ag+(aq) + Cl-(aq) Ksp= 1.8X10 -10
Silver Chloride Solubility
Silver Chloride Solubility
Silver chloride is known to be insoluble according to our solubility rules, but some does dissolve.
Silver chloride is known to be insoluble according to our solubility rules, but some does dissolve.
AgCl(s) Ag+(aq) + Cl-(aq) Ksp= 1.8X10 -10
Ksp = [Products]
[Reactants]= ?
Silver Chloride Solubility
Silver Chloride Solubility
Silver chloride is known to be insoluble according to our solubility rules, but some does dissolve.
Silver chloride is known to be insoluble according to our solubility rules, but some does dissolve.
AgCl(s) Ag+(aq) + Cl-(aq) Ksp= 1.8X10 -10
Ksp = [Ag+][Cl-]
Silver Chloride Solubility
Silver Chloride Solubility
Silver chloride is known to be insoluble according to our solubility rules, but some does dissolve.
Silver chloride is known to be insoluble according to our solubility rules, but some does dissolve.
AgCl(s) Ag+(aq) + Cl-(aq) Ksp= 1.8X10 -10
Ksp = [Ag+][Cl-] = [X][X] X2 = 1.8 X 10-10
X = 1.34 X 10-5 M
Silver Chloride Solubility
Silver Chloride Solubility
Silver chloride is known to be insoluble according to our solubility rules, but some does dissolve.
Silver chloride is known to be insoluble according to our solubility rules, but some does dissolve.
AgCl(s) Ag+(aq) + Cl-(aq) Ksp= 1.8X10 -10
Ksp = [Ag+][Cl-] = [X][X] X2 = 1.8 X 10-10
X = 1.34 X 10-5 M
1.34 X 10-5 mole Ag+
mole Ag+mole AgCl
L
142 g AgClmole AgCl
1.91 X 10-3 g AgCl will dissolve in a liter of water
Sample ProblemSample ProblemDetermine the molar solubility of magnesium hydroxide.Determine the molar solubility of magnesium hydroxide.
Sample ProblemSample ProblemDetermine the molar solubility of magnesium hydroxide.Determine the molar solubility of magnesium hydroxide.
Mg(OH)2 (s) Mg2+ + 2 OH- ksp= 1.8 X 10-11
Sample ProblemSample ProblemDetermine the molar solubility of magnesium hydroxide.Determine the molar solubility of magnesium hydroxide.
Mg(OH)2 (s) Mg2+ + 2 OH- ksp= 1.8 X 10-11
Ksp = [Mg2+][OH-]2
x 2x
Sample ProblemSample ProblemDetermine the molar solubility of magnesium hydroxide.Determine the molar solubility of magnesium hydroxide.
Mg(OH)2 (s) Mg2+ + 2 OH- ksp= 1.8 X 10-11
Ksp = [Mg2+][OH-]2 = x(2x)2 = 1.8 X 10-11
x 2x
x = 1.65 X 10-4 M
Sample ProblemSample ProblemDetermine the molar solubility of magnesium hydroxide.Determine the molar solubility of magnesium hydroxide.
Mg(OH)2 (s) Mg2+ + 2 OH- ksp= 1.8 X 10-11
Ksp = [Mg2+][OH-]2 = x(2x)2 = 1.8 X 10-11
x 2x
x = 1.65 X 10-4 M
[OH-] = 2(1.65x10-4) = 3.3x10--4
Sample ProblemSample ProblemDetermine the additional mass of magnesium hydroxide dissolved, after the addition of 125 mL of 1.00 X 10-4 M HCl.
Determine the additional mass of magnesium hydroxide dissolved, after the addition of 125 mL of 1.00 X 10-4 M HCl.Mg(OH)2 (s) Mg2+ + 2 OH- ksp= 1.8 X 10-11
Which way will the equilibrium shift?
Sample ProblemSample ProblemDetermine the additional mass of magnesium hydroxide dissolved, after the addition of 125 mL of 1.00 X 10-4 M HCl.
Determine the additional mass of magnesium hydroxide dissolved, after the addition of 125 mL of 1.00 X 10-4 M HCl.Mg(OH)2 (s) Mg2+ + 2 OH- ksp= 1.8 X 10-11
Which way will the equilibrium shift? Right
Sample ProblemSample ProblemDetermine the additional mass of magnesium hydroxide dissolved, after the addition of 125 mL of 1.00 X 10-4 M HCl.
Determine the additional mass of magnesium hydroxide dissolved, after the addition of 125 mL of 1.00 X 10-4 M HCl.Mg(OH)2 (s) Mg2+ + 2 OH- ksp= 1.8 X 10-11
Which way will the equilibrium shift? Right
What is the hydroxide ion concentration after addition of the HCl?
Sample ProblemSample ProblemDetermine the additional mass of magnesium hydroxide dissolved, after the addition of 125 mL of 1.00 X 10-4 M HCl.
Determine the additional mass of magnesium hydroxide dissolved, after the addition of 125 mL of 1.00 X 10-4 M HCl.Mg(OH)2 (s) Mg2+ + 2 OH- ksp= 1.8 X 10-11
Which way will the equilibrium shift? RightWhat is the hydroxide ion concentration after addition of the HCl?1.00 X 10-4 mole HCl
L
0.125 L= 1.25 X10-5 mole HCl
3.3x10-4 – 1.25x10-5 = 3.176 x 10-4 mole OH-
3.176x10-4 mole OH-
1.125 L = 2.822X104 M OH-
Sample ProblemSample ProblemWhat additional mass of Mg is dissolved
Ksp = [Mg2+][OH-]2 = 1.8 X 10-11
[Mg2+][OH-]2 = 1.8 X 10-11
[Mg2+][2.2822X10-4]2 = 1.8 X 10-11
[Mg2+] = 2.26X10-4M Mg2+
2.26X10-4M Mg2+ - 1.65X10 -4 Mg2+ (original) = 6.1 X10-5 moles Mg2+
6.1 X 10-5 moles Mg2+
moles Mg2+
24.3 g Mg2+
= 1.5 X 10-3 g Mg2+
About Dissolving Precipitates
About Dissolving Precipitates
Precipitates form when the product of the ion concentration Q>Ksp. Since precipitates are in equilibrium with the ions that form the LeChatelier’s Principle will control the solution process. The previous sample problem demonstrated how solubility is controlled by Ph. Clearly pH is dependent upon solubility and this is a very important consideration in qualitative analysis, which is always emphasized in prelab lectures. If the procedure states acidic or basic, use litmus paper. If the procedure states just basic, then use pH paper and adjust the pH to 8. If the procedure requires a specific pH, then use pH paper.
Solubility Controlling Factors
Solubility Controlling Factors
Since precipitate formation is related to solubility, then the following factors control precipitation also. These factors control the process, by adding or removing ions from the equilibrium mixture according to leChateliers principle.
The pH of the solutionremoving H+ or OH- by adding acid or base
Formation of a complexAdding a substance to form a coordination compound
Formation of a gasAdding a substance to convert one of the ions to a gas.
Since precipitate formation is related to solubility, then the following factors control precipitation also. These factors control the process, by adding or removing ions from the equilibrium mixture according to leChateliers principle.
The pH of the solutionremoving H+ or OH- by adding acid or base
Formation of a complexAdding a substance to form a coordination compound
Formation of a gasAdding a substance to convert one of the ions to a gas.
Dissolving AgCl (s)Dissolving AgCl (s)One of the most common applications of precipitate control by complex formation involves the insoluble silver chloride precipitate.
AgCl(s) Ag+(aq) + Cl-(aq) Ammonia will complex with silver ion to from the diamminosilver(I) complex, thus removing silver ion from solution. According to LeChatelier’s principle, silver chloride produces more silver ions which are then complexed with ammonia until all of the silver chloride solid is dissolved. The following slide illustrates this process quantitatively.
One of the most common applications of precipitate control by complex formation involves the insoluble silver chloride precipitate.
AgCl(s) Ag+(aq) + Cl-(aq) Ammonia will complex with silver ion to from the diamminosilver(I) complex, thus removing silver ion from solution. According to LeChatelier’s principle, silver chloride produces more silver ions which are then complexed with ammonia until all of the silver chloride solid is dissolved. The following slide illustrates this process quantitatively.
Complex FormationComplex FormationConsider silver complex formation with ammonia
Ag+ + NH3 ⇄ Ag(NH3)+ K1 = 2.1x103
Ag(NH3)+ + NH3 ⇄ Ag(NH3)2 K2 = 8.2x103
When using a large excess of NH3 and since the formation constants are large, the reaction can be considered to be complete, since the overall constant is 1.72x107.
Consider silver complex formation with ammonia
Ag+ + NH3 ⇄ Ag(NH3)+ K1 = 2.1x103
Ag(NH3)+ + NH3 ⇄ Ag(NH3)2 K2 = 8.2x103
When using a large excess of NH3 and since the formation constants are large, the reaction can be considered to be complete, since the overall constant is 1.72x107.
Ag+ + 2NH3 → Ag(NH3)2+ Kf = K1 x K2
Kf =1.72x107
Complex FormationComplex Formation Ag+ + 2NH3 → Ag(NH3)2
+
Given: [Ag+]i = 5x10-4 and [NH3]I = 1.0
Then [Ag+]f = 0 and [NH3]f = 1.0- 2(5x10-4), and [Ag(NH3)2
+]=5x10-4
Ag+ + 2NH3 → Ag(NH3)2+
Given: [Ag+]i = 5x10-4 and [NH3]I = 1.0
Then [Ag+]f = 0 and [NH3]f = 1.0- 2(5x10-4), and [Ag(NH3)2
+]=5x10-4
Yes, but there is a small amount of Ag+ so then how can we calculate this concentration? Next slide!
Complex FormationComplex FormationHow much [Ag(NH3)+] is present can be calculated using the K2
K2= [Ag(NH3)2+]/[NH3][ Ag(NH3)+]
Solving for [Ag(NH3)+] = [Ag(NH3)2+]/[NH3][ K2]
[Ag(NH3)+]=6.1x10-8, using 1.0 for ammonia
In a similar way, using K1, [Ag+] can be determined to be 2.9x10-11
How much [Ag(NH3)+] is present can be calculated using the K2
K2= [Ag(NH3)2+]/[NH3][ Ag(NH3)+]
Solving for [Ag(NH3)+] = [Ag(NH3)2+]/[NH3][ K2]
[Ag(NH3)+]=6.1x10-8, using 1.0 for ammonia
In a similar way, using K1, [Ag+] can be determined to be 2.9x10-11
Complex FormationComplex Formation
How do you dissolve and insoluble salt? For example AgCl
The equilibrium is AgCl ⇄ Ag+ + Cl-
Need to shift the equilibrium to the right to dissolve the solid AgCl
Consider the following process
AgCl ⇄ Ag+ + Cl- Ksp=1.6x10-10
Ag+ + NH3 ⇄ Ag(NH3) K1 = 2.1x103
Ag(NH3)+ + NH3 ⇄ Ag(NH3)2+ K2 = 8.2x103
AgCl (s) + 2NH3 ⇄ Ag(NH3)2+ + Cl- K1xK2x Ksp
How do you dissolve and insoluble salt? For example AgCl
The equilibrium is AgCl ⇄ Ag+ + Cl-
Need to shift the equilibrium to the right to dissolve the solid AgCl
Consider the following process
AgCl ⇄ Ag+ + Cl- Ksp=1.6x10-10
Ag+ + NH3 ⇄ Ag(NH3) K1 = 2.1x103
Ag(NH3)+ + NH3 ⇄ Ag(NH3)2+ K2 = 8.2x103
AgCl (s) + 2NH3 ⇄ Ag(NH3)2+ + Cl- K1xK2x Ksp
Complex FormationComplex Formation
AgCl (s) + 2NH3 ⇄ Ag(NH3)2+ + Cl- K =2.8x103
Use the equilibria expression above to calculate the solubility of AgCl in a 10.0 M ammonia solution
K = [Ag(NH3)2+][Cl-]/[NH3]2 → 2.8x10-3 = x2/ (10-2x)2
X=0.48 M
AgCl (s) + 2NH3 ⇄ Ag(NH3)2+ + Cl- K =2.8x103
Use the equilibria expression above to calculate the solubility of AgCl in a 10.0 M ammonia solution
K = [Ag(NH3)2+][Cl-]/[NH3]2 → 2.8x10-3 = x2/ (10-2x)2
X=0.48 M
10.0 0 0 initial
10-2x x x
The EndThe End