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C h a p t e rC h a p t e r 2020Transition Elements and Coordination ChemistryTransition Elements and Coordination Chemistry
Chapter 20 Slide 2
Chem 1A Review Chem 1A Review
Why Study Coordinated Complexes of Transition metals?
These compounds are used as catalyst in oxidation of organic compounds and pharmaceutical applications.
Chapter 20 Slide 3
Order of orbitals (filling) in multi-electron atom
1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s< 4f< 5d< 6p< 7s< 5f< 6d< 7p
Chapter 20 Slide 4
Chapter 20 Slide 5
ns1
ns2
ns2
np1
ns2
np2
ns2
np3
ns2
np4
ns2
np5
ns2
np6
d1
d5 d10
4f
5f
Electron Configuration and the Periodic Table
Slide 6
a)S [Ne]3s23p4
Using periodic table write Noble gas notation for the following elements:
b)Fe[Ar] 4s23d6
c)Se [Ar] 4s23d104p4
d)Gd [Xe]6s24f75d1
1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s< 4f< 5d< 6p< 7s< 5f< 6d< 7p
Chapter 20 Slide 7
Chapter 20 Slide 8
Electron ConfigurationsElectron Configurations
Chapter 20 Slide 9
Why Study Coordinated Complexes of Transition metals? Are used as catalyst in oxidation of organic compounds.Medicinal applications.
““Cisplatin” - a cancer Cisplatin” - a cancer chemotherapy agentchemotherapy agent
Chapter 20 Slide 10
Coordination CompoundsCoordination Compounds
Co(HCo(H22O)O)662+2+
Pt(NHPt(NH33))22ClCl22
Cu(NHCu(NH33))442+2+
““Cisplatin” - a cancer Cisplatin” - a cancer chemotherapy agentchemotherapy agent
Chapter 20 Slide 11
Coordination Coordination Compounds of Compounds of NiNi2+2+
Coordination Coordination Compounds of Compounds of NiNi2+2+
[Ni(NH[Ni(NH22CC22HH44NHNH22))33]]+2+2
[Ni(NH[Ni(NH33))66]]+2+2
Chapter 20 Slide 12
Electron ConfigurationsElectron Configurations
Zn (Z = 30): [Ar] 3d10 4s2Sc (Z = 21): [Ar] 3d1 4s2
Chapter 20 Slide 13
Coordination Compounds
Many coordination compound consists of a complex ion.
A complex ion contains a central metal cation bonded to one or more molecules or ions.
The molecules or ions that surround the metal in a complex ion are called ligands.
A ligand has at least one unshared pair of valence electrons
H
O
H
• ••• • •
H
N
HH• •
••Cl• •
••
-
••C O••
Omit 20.2 - 20.4
Chapter 20 Slide 14
Coordination Compounds
The atom in a ligand that is bound directly to the metal atom is the donor atom.
H
O
H
• ••• • •
H
N
HH
Ligands with:
one donor atom monodentate
two donor atoms bidentate
three or more donor atoms polydentate
H2O, NH3, Cl-
ethylenediamine
EDTA
The number of donor atoms surrounding the central metal atom in a complex ion is the coordination number.
Chapter 20 Slide 15
Coordination CompoundsCoordination Compounds
Coordination Number: The number of ligand donor atoms that surround a central metal ion or atom.
Chapter 20 Slide 16
Ligands 02Ligands 02
Chapter 20 Slide 17
Ligands 03Ligands 03
Chapter 20 Slide 18
Poly DentateLigandsPoly DentateLigands
• EDTA4– is often used to treat heavy metal poisoning such as Hg2+, Pb2+, and Cd2+.
• EDTA4– bonds to Pb2+, which is excreted by the kidneys as [Pb(EDTA)]2–.
Chapter 20 Slide 19
Coordination Compounds
H2N CH2 CH2 NH2
• • • •
bidentate ligand polydentate ligand(EDTA)
Bidentate and polydentate ligands are called chelating agents
Chapter 20 Slide 20
What is the Oxidation Numbers of Cu?What is the Oxidation Numbers of Cu?
Knowing the charge on a complex ion and the charge on each ligand, one can determine the oxidation number for the metal.
Naming coordinated complex compounds
+2
Chapter 20 Slide 21
Rule Applies to Statement
1 Elements The oxidation number of an atom in an element is zero.
2 Monatomic ions The oxidation number of an atom in a monatomic ion equals the charge of the ion.
3 Oxygen The oxidation number of oxygen is –2 in most of its compounds. (An exception is O in H2O2 and other peroxides, where the oxidation number is –1.)
OxidationNumber RulesOxidationNumber Rules
Chapter 20 Slide 22
Oxidation Number RulesOxidation Number Rules
Rule Applies to Statement
4 Hydrogen +1, it will be -1 when hydrogen comes with metal. NaH
5 Halogens Fluorine is –1 in all its compounds. Each of the other halogens is –1 in binary compounds unless the other element is oxygen.
6 Compounds and ions
The sum of the oxidation numbers of the atoms in a compound is zero. The sum in a polyatomic ion equals the charge on the ion.
Chapter 20 Slide 23
What is the charge on the following Complex, If the Oxidation number of Cr is +3?What is the charge on the following Complex, If the Oxidation number of Cr is +3?
Or, knowing the oxidation number on the metal and the charges on the ligands, one can calculate the charge on the complex ion.
Chapter 20 Slide 24
What are the oxidation numbers of the metals in K[Au(OH)4] and [Cr(NH3)6](NO3)3 ?
OH- has charge of -1
K+ has charge of +1
? Au + 1 + 4x(-1) = 0
Au = +3
NO3- has charge of -1
NH3 has no charge
? Cr + 6x(0) + 3x(-1) = 0
Cr = +3
Chapter 20 Slide 25
Oxidation States of the 1st Row Transition Metals(most stable oxidation numbers are shown in red)
Chapter 20 Slide 26
Learning CheckLearning Check
A complex ion contains a Cr3+ bound to four H2O molecules and two Cl– ions. Write its formula.
+1
Chapter 20 Slide 27
Coordination Sphere Coordination Sphere
• Coordinate bond:
• Coordination Sphere: is the central metal and surrounding ligands. The square brackets separate the complex from counter ions such as SO4
2–.
H
H
H
H
H
H
H
H
+
H
H
H
H
Ag+(aq) 2 Ag+
[Ag(NH3)2]2 SO4
N N N
Chapter 20 Slide 28
Geometry of Coordination Compounds
Coordination number Structure2
4
6
Linear
Tetrahedral or Square planar (mostly d8 )
Octahedral
Chapter 20 Slide 29
Coordination Number of 7&8Coordination Number of 7&8
• Geometry
Pentagonal bipyramid Hexagonal bipyramid
Coordination Number of 8Coordination Number of 7
Chapter 20 Slide 30
Coordination CompoundsCoordination Compounds
• Geometries:
Chapter 20 Slide 31
NomenclatureNomenclature
Co(HCo(H22O)O)662+2+
Pt(NHPt(NH33))22ClCl22
Cu(NHCu(NH33))442+2+
Hexaaquacobalt(II)Hexaaquacobalt(II)
Tetraamminecopper(II)Tetraamminecopper(II)
diamminedichloroplatinum(II)diamminedichloroplatinum(II)
HH22O as a ligand is O as a ligand is aquaaqua
NHNH33 as a ligand is as a ligand is ammineammine
Systematic naming specifies the type and number of ligands, the metal, and its oxidation state.
Chapter 20 Slide 32
Ligand’s Names 01Ligand’s Names 01
Chapter 20 Slide 33
Chapter 20 Slide 34
NomenclatureNomenclature
Chapter 20 Slide 35
NomenclatureNomenclature
• Systematic naming follows IUPAC rules:
• If compound is a salt, name cation first and then the anion, just as in naming simple salts.
• In naming a complex ion or neutral complex, name ligands first and then the metal.
• If the complex contains more than one ligand of a particular type, indicate the number with the appropriate Greek prefix: di–, tri–, tetra–, penta–, hexa–.
Chapter 20 Slide 36
NomenclatureNomenclature
• If the name of a ligand itself contains a Greek prefix,
(ethylenediamine or tritriphenylphosphinephenylphosphine) put the ligand name in
parentheses and use: bis (2), tris (3), or tetrakis (4).
• Use a Roman numeral in parentheses, immediately following the
name of the metal, to indicate the metal’s oxidation state.
• In naming the metal, use the ending –ate if metal is in an anionic
complex.
Chapter 20 Slide 37
Name the following Complexes:Name the following Complexes:
Pt(Tris(ethylenediamine)nickel(II)Tris(ethylenediamine)nickel(II)
IrCl(CO)(PPhIrCl(CO)(PPh33))22
Carbonylchlorobis(triphenylphosphine)iridium(I)Carbonylchlorobis(triphenylphosphine)iridium(I)
[Ni(NH[Ni(NH22CC22HH44NHNH22))33]]2+2+
Chapter 20 Slide 38
What is the systematic name of [Cr(H2O)4Cl2]Cl ?
tetraaquadichlorochromium(III) chloride
Write the formula of tris(ethylenediamine)cobalt(II) sulfate
[Co(en)3]SO4
Chapter 20 Slide 39
1. Constitutional Isomers: Have different bonds among their constituent atoms.
• Ionization Isomers :
[Co(NH3)5Br]SO4 (violet compound with Co–Br bond),
[Co(NH3)5 SO4]Br (red compound with Co–SO4 bond).
• Linkage Isomers form when a ligand can bond through two different donor atoms. Consider [Co(NH3)5NO2]2+
which is yellow with the Co–NO2 bond and red with the
Co–ONO bond.
Constitutional IsomerismConstitutional IsomerismConstitutional IsomerismConstitutional Isomerism
Chapter 20 Slide 40
Linkage IsomerismLinkage IsomerismLinkage IsomerismLinkage Isomerism
CoH3N
H3N NO2
NH3
NH3
NH3
2+
CoH3N
H3N ONO
NH3
NH3
NH3
2+
sunlightsunlight
Such a transformation could be used as an energy Such a transformation could be used as an energy storage device.storage device.
Slide 41
2.Stereoisomers 2.Stereoisomers
• Geometric Isomers of Pt(NH3)2Cl2: In the cis
isomer, atoms are on the same side. In the trans
isomer, atoms are on opposite sides.
DNA-damaging antitumor agents Inactive
Chapter 20 Slide 42
2.Stereoisomers2.Stereoisomers
Geometric Isomers have the same connections among atoms but different spatial orientations of the metal–ligand bonds.
a)cis isomers have identical ligands in adjacent corners of a square.
b)trans isomers have identical ligands across the corners from each other.
Chapter 20 Slide 43
• Geometric Isomers of [Co(NH3)4Cl2]Cl:
IsomersIsomers
Chapter 20 Slide 44
Enantiomers Enantiomers
Chapter 20 Slide 45
• An object or compound is achiral if it has a symmetry plane cutting through the middle.
Enantiomers Enantiomers
•Enantiomers are stereoisomers of molecules or ions
that are nonidentical mirror images of each other.
•Objects that have “handedness” are said to be chiral,
and objects that lack “handedness” are said to be achiral.
Chapter 20 Slide 46
EnantiomersEnantiomers
Chapter 20 Slide 47 Unpolarized light. Unpolarized light.
© 2003 John Wiley and Sons Publishers
Chapter 20 Slide 48 Plane-polarized light. Plane-polarized light.
© 2003 John Wiley and Sons Publishers
plane-polarized light plane-polarized light
Chapter 20 Slide 49 Reflected glare is plane-polarized light. Reflected glare is plane-polarized light.
© 2003 John Wiley and Sons Publishers
Chapter 20 Slide 50 Polarizing sunglasses versus glare. Polarizing sunglasses versus glare.
© 2003 John Wiley and Sons Publishers
Chapter 20 Slide 51The effect of polarizing lenses on unpolarized light.The effect of polarizing lenses on unpolarized light.
© 2003 John Wiley and Sons Publishers
Courtesy Andy Washnik
Chapter 20 Slide 52
plane-polarized light plane-polarized light
Chapter 20 Slide 53
Enantiomers and Molecular HandednessEnantiomers and Molecular Handedness
Chapter 20 Slide 54
EnantiomersEnantiomers
Enantiomers have identical properties except for their reaction with other chiral substances and their effect on plane-polarized light.
•Enantiomers are often called optical isomers; their
effect on plane-polarized light can be measured with
a polarimeter.
Chapter 20 Slide 55
EnantiomersEnantiomers
• Plane-polarized light is obtained by passing ordinary light through a polarizing filter.
• In a polarimeter the plane-polarized light is passed through a chiral solution and the polarization plane measured with an analyzing filter.
• If the plane rotates to the right it is dextrorotatory.
• If the plane rotates to the left it is levorotatory.
• Equal amounts of each are racemic.
Chapter 20 Slide 56
Isomers 01Isomers 01
Slide 57
CoH3N
H3N NO2
NH3
NH3
NH3
2+
CoH3N
H3N ONO
NH3
NH3
NH3
2+
sunlightsunlight
[Co(NH3)5Br]SO4 (violet),
[Co(NH3)5 SO4]Br (red ).
See next slide for Diastereoisomers
Chapter 20 Slide 58
DiasteromersDiasteromers
Chapter 20 Slide 59
Bonding in Complexes 01Bonding in Complexes 01
• Bonding Theories attempt to account for the color and magnetic properties of transition metal complexes.
Ni2+ Cu2+Ni2+ Cu2+
Zn2+ Zn2+Co2+Co2+•Solutions of [Ni(H2O)6]2+, [Ni(NH3)6]2+, & [Ni(en)3]2+
Chapter 20 Slide 60
Color of Transition Metal ComplexesColor of Transition Metal Complexes
or
E
hc =
E = E2 - E1 = h =hc
Chapter 20 Slide 61
Color of Transition Metal ComplexesColor of Transition Metal Complexes
Chapter 20 Slide 62
Color of Transition Metal ComplexesColor of Transition Metal Complexes
Chapter 20 Slide 63
Bonding in Complexes: Valence Bond TheoryBonding in Complexes: Valence Bond Theory
Chapter 20 Slide 64
Bonding in Complexes: Which empty orbital is metal using for bondingS, p, d or f ?
Bonding in Complexes: Which empty orbital is metal using for bondingS, p, d or f ?
Chapter 20 Slide 65
Hybridization and sp3 Hybrid OrbitalsHybridization and sp3 Hybrid Orbitals
How can the bonding in CH4 be explained?
4 valence electrons2 unpaired electrons
Chapter 20 Slide 66
Hybridization and sp3 Hybrid OrbitalsHybridization and sp3 Hybrid Orbitals
4 valence electrons4 unpaired electrons
How can the bonding in CH4 be explained?
Chapter 20 Slide 67
Hybridization and sp3 Hybrid OrbitalsHybridization and sp3 Hybrid Orbitals
4 nonequivalent orbitals
How can the bonding in CH4 be explained?
Chapter 20 Slide 68
Hybridization and sp3 Hybrid OrbitalsHybridization and sp3 Hybrid Orbitals
4 equivalent orbitals
How can the bonding in CH4 be explained?
Chapter 20 Slide 69
Hybridization and sp3 Hybrid OrbitalsHybridization and sp3 Hybrid Orbitals
Chapter 20 Slide 70
Hybridization and sp3 Hybrid OrbitalsHybridization and sp3 Hybrid Orbitals
Chapter 20 Slide 71
Other Kinds of Hybrid OrbitalsOther Kinds of Hybrid Orbitals
Slide 72
Hybrid Orbitals in Coordinated ComplexesHybrid Orbitals in Coordinated Complexes
We should look at magnetic property of the complex to see if they are high or low spin. Then we could decide whether they are using d2sp3 or sp3d2 hybrid
Chapter 20 Slide 73
The octahedral d2sp3 and sp3d2The octahedral d2sp3 and sp3d2
Chapter 20 Slide 74
Square Planar geometry of four dsp2Square Planar geometry of four dsp2
Chapter 20 Slide 75
Bonding in Complexes: Valence Bond TheoryBonding in Complexes: Valence Bond Theory
Experimental results: High Spin
Chapter 20 Slide 76
Bonding in Complexes: Valence Bond TheoryBonding in Complexes: Valence Bond Theory
Experimental results: Low Spin
Chapter 20 Slide 77
High- and Low-Spin ComplexesHigh- and Low-Spin Complexes
Low spin: Minimum number of unpaired electron
High spin: Maxium number of unpaired electron, Paramagnetic
Experimental results : High Spin[CoF6]3-
[Co(CN)6]3-
Chapter 20 Slide 78
Crystal Field TheoryCrystal Field Theory
Crystal Field Theory: Effect of charges of ligand on transition metal d-electrons.
A model that views the bonding in complexes as arising from electrostatic interactions and considers the effect of the ligand charges on the energies of the metal ion d orbitals.
Chapter 20 Slide 79
Crystal Field TheoryCrystal Field Theory
Directed at ligands
Directed between ligands
Octahedral Complexes
Chapter 20 Slide 80
Crystal Field TheoryCrystal Field TheoryOctahedral Complexes
Chapter 20 Slide 81
Crystal Field TheoryCrystal Field Theory
[Ni(X)6]2+ X=H2O, NH3, and ethylenediamine (en)
Octahedral Complexes
(red-violet)
[Ti(H2O)6]3+[Ti(H2O)6]3+
Chapter 20 Slide 82
Chapter 20 Slide 83
Crystal Field TheoryCrystal Field Theory
[Ni(X)6]2+ X=H2O, NH3, and ethylenediamine (en)
Octahedral Complexes
The crystal field splitting changes depending on nature of the legand.
Chapter 20 Slide 84
The absorption maximum for the complex ion [Co(NH3)6]3+ occurs at 470 nm. What is the color of the complex and what is the crystal field splitting in kJ/mol?
E = h hc= = 4.23 x 10-19 J
(kJ/mol) ?
= 255 kJ/mol
