AP*
Chapter 21
Transition Metals and
Coordination Chemistry
AP Learning Objectives
 LO 1.10 Students can justify with evidence the arrangement of the periodic
table and can apply periodic properties to chemical reactivity. (Sec 21.1)
 LO 1.11 The student can analyze data, based on periodicity and the properties
of binary compounds, to identify patterns and generate hypotheses related to
the molecular design of compounds for which data are not supplied. (Sec 21.1)
Section 21.1
The Transition Metals: A Survey
AP Learning Objectives, Margin Notes and References
 Learning Objectives


LO 1.10 Students can justify with evidence the arrangement of the periodic table and can apply periodic properties
to chemical reactivity.
LO 1.11 The student can analyze data, based on periodicity and the properties of binary compounds, to identify
patterns and generate hypotheses related to the molecular design of compounds for which data are not supplied.
Section 21.1
The Transition Metals: A Survey
Transition Metals
 Show great similarities within a given period as well
as within a given vertical group.
Copyright © Cengage Learning. All rights reserved
4
Section 21.1
The Transition Metals: A Survey
The Position of the Transition Elements on the Periodic
Table
Copyright © Cengage Learning. All rights reserved
5
Section 21.1
The Transition Metals: A Survey
Forming Ionic Compounds
 More than one oxidation state is often found.
 Cations are often complex ions – species where the
transition metal ion is surrounded by a certain
number of ligands (Lewis bases).
Copyright © Cengage Learning. All rights reserved
6
Section 21.1
The Transition Metals: A Survey
The Complex Ion Co(NH3)63+
Copyright © Cengage Learning. All rights reserved
7
Section 21.1
The Transition Metals: A Survey
Ionic Compounds with Transition Metals
 Most compounds are colored because the transition
metal ion in the complex ion can absorb visible light
of specific wavelengths.
 Many compounds are paramagnetic.
Copyright © Cengage Learning. All rights reserved
8
Section 21.1
The Transition Metals: A Survey
Electron Configurations
 Example
 V: [Ar]4s23d3
 Exceptions: Cr and Cu
 Cr: [Ar]4s13d5
 Cu: [Ar]4s13d10
Copyright © Cengage Learning. All rights reserved
9
Section 21.1
The Transition Metals: A Survey
Electron Configurations
 First-row transition metal ions do not have 4s
electrons.
 Energy of the 3d orbitals is significantly less than
that of the 4s orbital.
Ti: [Ar]4s23d2
Ti3+: [Ar]3d1
Copyright © Cengage Learning. All rights reserved
10
Section 21.1
The Transition Metals: A Survey
CONCEPT CHECK!
What is the expected electron configuration of
Sc+?
Explain.
[Ar]3d2
Copyright © Cengage Learning. All rights reserved
11
Section 21.1
The Transition Metals: A Survey
Plots of the First (Red Dots) and Third (Blue Dots) Ionization
Energies for the First-Row Transition Metals
Copyright © Cengage Learning. All rights reserved
12
Section 21.1
The Transition Metals: A Survey
Atomic Radii of the 3d, 4d, and 5d Transition Series
Copyright © Cengage Learning. All rights reserved
13
Section 21.2
The First-Row Transition Metals

3d transition metals
 Scandium – chemistry strongly resembles lanthanides
 Titanium – excellent structural material (light weight)
 Vanadium – mostly in alloys with other metals
 Chromium – important industrial material
 Manganese – production of hard steel
 Iron – most abundant heavy metal
 Cobalt – alloys with other metals
 Nickel – plating more active metals; alloys
 Copper – plumbing and electrical applications
 Zinc – galvanizing steel
Copyright © Cengage Learning. All rights reserved
14
Section 21.2
The First-Row Transition Metals
Oxidation States and Species for Vanadium in Aqueous Solution
Copyright © Cengage Learning. All rights reserved
15
Section 21.2
The First-Row Transition Metals
Typical Chromium Compounds
Copyright © Cengage Learning. All rights reserved
16
Section 21.2
The First-Row Transition Metals
Some Compounds of Manganese in Its Most Common
Oxidation States
Copyright © Cengage Learning. All rights reserved
17
Section 21.2
The First-Row Transition Metals
Typical Compounds
of Iron
Section 21.2
The First-Row Transition Metals
Typical Compounds
of Cobalt
Section 21.2
The First-Row Transition Metals
Typical Compounds
of Nickel
Copyright © Cengage Learning. All rights reserved
20
Section 21.2
The First-Row Transition Metals
Typical Compounds of Copper
Section 21.2
The First-Row Transition Metals
Alloys Containing Copper
Copyright © Cengage Learning. All rights reserved
22
Section 21.3
Coordination Compounds
A Coordination Compound
 Typically consists of a complex ion and counterions
(anions or cations as needed to produce a neutral
compound):
[Co(NH3)5Cl]Cl2
[Fe(en)2(NO2)2]2SO4
K3Fe(CN)6
Copyright © Cengage Learning. All rights reserved
23
Section 21.3
Coordination Compounds
Coordination Number
 Number of bonds formed between the metal ion and
the ligands in the complex ion.
 6 and 4 (most common)
 2 and 8 (least common)
Copyright © Cengage Learning. All rights reserved
24
Section 21.3
Coordination Compounds
Ligands
 Neutral molecule or ion having a lone electron pair that
can be used to form a bond to a metal ion.
 Monodentate ligand – one bond to a metal ion
 Bidentate ligand (chelate) – two bonds to a metal ion
 Polydentate ligand – more than two bonds to a metal
ion
Copyright © Cengage Learning. All rights reserved
25
Section 21.3
Coordination Compounds
Coordinate Covalent Bond
 Bond resulting from the interaction between a Lewis
base (the ligand) and a Lewis acid (the metal ion).
Copyright © Cengage Learning. All rights reserved
26
Section 21.3
Coordination Compounds
The Bidentate Ligand
Ethylenediamine and the
Monodentate Ligand
Ammonia
Section 21.3
Coordination Compounds
The Coordination of EDTA
with a 2+ Metal Ion
ethylenediaminetetraacetate
Copyright © Cengage Learning. All rights reserved
28
Section 21.3
Coordination Compounds
Rules for Naming Coordination Compounds
[Co(NH3)5Cl]Cl2
1. Cation is named before the anion.
“chloride” goes last (the counterion)
2. Ligands are named before the metal ion.
ammonia (ammine) and chlorine
(chloro) named before cobalt
Section 21.3
Coordination Compounds
Rules for Naming Coordination Compounds
[Co(NH3)5Cl]Cl2
3. For negatively charged ligands, an “o” is added to the
root name of an anion (such as fluoro, bromo, chloro,
etc.).
4. The prefixes mono-, di-, tri-, etc., are used to denote the
number of simple ligands.
penta ammine
Copyright © Cengage Learning. All rights reserved
30
Section 21.3
Coordination Compounds
Rules for Naming Coordination Compounds
[Co(NH3)5Cl]Cl2
5. The oxidation state of the central metal ion is
designated by a Roman numeral:
cobalt (III)
6. When more than one type of ligand is present, they are
named alphabetically:
pentaamminechloro
Copyright © Cengage Learning. All rights reserved
31
Section 21.3
Coordination Compounds
Rules for Naming Coordination Compounds
[Co(NH3)5Cl]Cl2
7. If the complex ion has a negative charge, the suffix
“ate” is added to the name of the metal.
The correct name is:
pentaamminechlorocobalt(III) chloride
Copyright © Cengage Learning. All rights reserved
32
Section 21.3
Coordination Compounds
EXERCISE!
Name the following coordination compounds.
a) [Co(H2O)6]Br3
hexaaquacobalt(III) bromide
b) Na2[PtCl4]
sodiumtetrachloro-platinate(II)
Copyright © Cengage Learning. All rights reserved
33
Section 21.4
Isomerism
Some Classes of Isomers
Section 21.4
Isomerism
Structural Isomerism
 Coordination Isomerism:
 Composition of the complex ion varies.
 [Cr(NH3)5SO4]Br and [Cr(NH3)5Br]SO4
 Linkage Isomerism:
 Composition of the complex ion is the same, but
the point of attachment of at least one of the
ligands differs.
Copyright © Cengage Learning. All rights reserved
35
Section 21.4
Isomerism
Linkage Isomerism of NO2–
Section 21.4
Isomerism
Stereoisomerism
 Geometrical Isomerism (cis-trans):
 Atoms or groups of atoms can assume different
positions around a rigid ring or bond.
 Cis – same side (next to each other)
 Trans – opposite sides (across from each other)
Copyright © Cengage Learning. All rights reserved
37
Section 21.4
Isomerism
Geometrical (cis-trans)
Isomerism for a Square
Planar Compound
a) cis isomer
b) trans isomer
Section 21.4
Isomerism
Geometrical (cis-trans) Isomerism for an Octahedral
Complex Ion
Copyright © Cengage Learning. All rights reserved
39
Section 21.4
Isomerism
Stereoisomerism
 Optical Isomerism:
 Isomers have opposite effects on plane-polarized
light.
Copyright © Cengage Learning. All rights reserved
40
Section 21.4
Isomerism
Unpolarized Light Consists of Waves Vibrating in Many
Different Planes
Copyright © Cengage Learning. All rights reserved
41
Section 21.4
Isomerism
The Rotation of the Plane of Polarized Light by an Optically
Active Substance
Copyright © Cengage Learning. All rights reserved
42
Section 21.4
Isomerism
Optical Activity
 Exhibited by molecules that have nonsuperimposable
mirror images (chiral molecules).
 Enantiomers – isomers of nonsuperimposable mirror
images.
Copyright © Cengage Learning. All rights reserved
43
Section 21.4
Isomerism
A Human Hand Exhibits a Nonsuperimposable Mirror Image
Copyright © Cengage Learning. All rights reserved
44
Section 21.4
Isomerism
CONCEPT CHECK!
Does [Co(en)2Cl2]Cl exhibit geometrical isomerism?
Yes
Does it exhibit optical isomerism?
Trans form – No
Cis form – Yes
Explain.
Copyright © Cengage Learning. All rights reserved
45
Section 21.5
Bonding in Complex Ions:
The Localized Electron Model
Bonding in Complex Ions
1. The VSEPR model for predicting structure generally does
not work for complex ions.
 However, assume a complex ion with a coordination
number of 6 will have an octahedral arrangement of
ligands.
 And, assume complexes with two ligands will be
linear.
 But, complexes with a coordination number of 4 can
be either tetrahedral or square planar.
Copyright © Cengage Learning. All rights reserved
46
Section 21.5
Bonding in Complex Ions:
The Localized Electron Model
Bonding in Complex Ions
2. The interaction between a metal ion and a ligand can be
viewed as a Lewis acid–base reaction with the ligand
donating a lone pair of electrons to an empty orbital of
the metal ion to form a coordinate covalent bond.
Copyright © Cengage Learning. All rights reserved
47
Section 21.5
Bonding in Complex Ions:
The Localized Electron Model
The Interaction Between a Metal Ion and a Ligand Can Be
Viewed as a Lewis Acid-Base Reaction
Copyright © Cengage Learning. All rights reserved
48
Section 21.5
Bonding in Complex Ions:
The Localized Electron Model
Hybrid Orbitals on Co3+ Can Accept an Electron Pair from
Each NH3 Ligand
Section 21.5
Bonding in Complex Ions:
The Localized Electron Model
The Hybrid Orbitals Required for
Tetrahedral, Square Planar, and
Linear Complex Ions
Section 21.6
The Crystal Field Model
 Focuses on the energies of the d orbitals.
Assumptions
1. Ligands are negative point charges.
2. Metal–ligand bonding is entirely ionic:
 strong-field (low–spin):
large splitting of d orbitals
 weak-field (high–spin):
small splitting of d orbitals
Copyright © Cengage Learning. All rights reserved
51
Section 21.6
The Crystal Field Model
Octahedral Complexes
 d z and d x  y point their lobes directly at the pointcharge ligands.
 d xz , d yz ,and d xy point their lobes between the point
charges.
2
2
2
Copyright © Cengage Learning. All rights reserved
52
Section 21.6
The Crystal Field Model
An Octahedral Arrangement of Point-Charge Ligands and
the Orientation of the 3d Orbitals
Copyright © Cengage Learning. All rights reserved
53
Section 21.6
The Crystal Field Model
Which Type of Orbital is Lower in Energy?
 Because the negative point-charge ligands repel
negatively charged electrons, the electrons will first fill
the d orbitals farthest from the ligands to minimize
repulsions.
 The d xz , d yz ,and d xy orbitals are at a lower energy in the
octahedral complex than are the
d z and d x  y orbitals.
2
2
2
Copyright © Cengage Learning. All rights reserved
54
Section 21.6
The Crystal Field Model
The Energies of the 3d Orbitals for a Metal Ion in an
Octahedral Complex
Copyright © Cengage Learning. All rights reserved
55
Section 21.6
The Crystal Field Model
Possible Electron Arrangements in the Split 3d
Orbitals in an Octahedral Complex of Co3+
Section 21.6
The Crystal Field Model
Magnetic Properties
 Strong–field (low–spin):
 Yields the minimum number of unpaired electrons.
 Weak–field (high–spin):
 Gives the maximum number of unpaired electrons.
 Hund’s rule still applies.
Copyright © Cengage Learning. All rights reserved
57
Section 21.6
The Crystal Field Model
Spectrochemical Series
 Strong–field ligands to weak–field ligands.
(large split)
(small split)
CN– > NO2– > en > NH3 > H2O > OH– > F– > Cl– > Br– > I–
 Magnitude of split for a given ligand increases as the
charge on the metal ion increases.
Section 21.6
The Crystal Field Model
Complex Ion Colors
 When a substance absorbs certain wavelengths of light
in the visible region, the color of the substance is
determined by the wavelengths of visible light that
remain.
 Substance exhibits the color complementary to those
absorbed.
Copyright © Cengage Learning. All rights reserved
59
Section 21.6
The Crystal Field Model
Complex Ion Colors
 The ligands coordinated to a given metal ion determine
the size of the d–orbital splitting, thus the color changes
as the ligands are changed.
 A change in splitting means a change in the wavelength
of light needed to transfer electrons between the t2g and
eg orbitals.
Copyright © Cengage Learning. All rights reserved
60
Section 21.6
The Crystal Field Model
Absorbtion of Visible Light by the Complex Ion Ti(H2O)63+
Copyright © Cengage Learning. All rights reserved
61
Section 21.6
The Crystal Field Model
CONCEPT CHECK!
Which of the following are expected to form colorless
octahedral compounds?
Zn2+
Cu+
Fe3+
Fe2+
Cr3+
Cu2+
Mn2+
Ti4+
Ni2+
Ag+
Section 21.6
The Crystal Field Model
Tetrahedral Arrangement
 None of the 3d orbitals “point at the ligands”.
 Difference in energy between the split d orbitals is
significantly less.
 d–orbital splitting will be opposite to that for the
octahedral arrangement.
 Weak–field case (high–spin) always applies.
Copyright © Cengage Learning. All rights reserved
63
Section 21.6
The Crystal Field Model
The d Orbitals in a Tetrahedral Arrangement of Point
Charges
Copyright © Cengage Learning. All rights reserved
64
Section 21.6
The Crystal Field Model
The Crystal Field Diagrams for Octahedral and Tetrahedral
Complexes
Copyright © Cengage Learning. All rights reserved
65
Section 21.6
The Crystal Field Model
CONCEPT CHECK!
Consider the Crystal Field Model (CFM).
a) Which is lower in energy, d–orbital lobes
pointing toward ligands or between ? Why?
b) The electrons in the d–orbitals – are they
from the metal or the ligands?
Copyright © Cengage Learning. All rights reserved
66
Section 21.6
The Crystal Field Model
CONCEPT CHECK!
Consider the Crystal Field Model (CFM).
c) Why would electrons choose to pair up in d–
orbitals instead of being in separate orbitals?
d) Why is the predicted splitting in tetrahedral
complexes smaller than in octahedral complexes?
Copyright © Cengage Learning. All rights reserved
67
Section 21.6
The Crystal Field Model
CONCEPT CHECK!
Using the Crystal Field Model, sketch possible
electron arrangements for the following. Label one
sketch as strong field and one sketch as weak field.
a) Ni(NH3)62+
b) Fe(CN)63–
c) Co(NH3)63+
Copyright © Cengage Learning. All rights reserved
68
Section 21.6
The Crystal Field Model
CONCEPT CHECK!
A metal ion in a high–spin octahedral complex has 2
more unpaired electrons than the same ion does in a
low–spin octahedral complex.
What are some possible metal ions for which this
would be true?
Metal ions would need to be d4 or d7 ions.
Examples include Mn3+, Co2+, and Cr2+.
Copyright © Cengage Learning. All rights reserved
69
Section 21.6
The Crystal Field Model
CONCEPT CHECK!
Between [Mn(CN)6]3– and [Mn(CN)6]4– which is more
likely to be high spin? Why?
Copyright © Cengage Learning. All rights reserved
70
Section 21.6
The Crystal Field Model
The d Energy Diagrams
for Square Planar
Complexes
Copyright © Cengage Learning. All rights reserved
71
Section 21.6
The Crystal Field Model
The d Energy
Diagrams for Linear
Complexes Where the
Ligands Lie Along the z
Axis
Copyright © Cengage Learning. All rights reserved
72
Section 21.7
The Biological Importance
of Coordination Complexes
 Metal ion complexes are used in humans for the
transport and storage of oxygen, as electron-transfer
agents, as catalysts, and as drugs.
Copyright © Cengage Learning. All rights reserved
73
Section 21.7
The Biological Importance
of Coordination Complexes
First-Row Transition Metals and Their Biological Significance
Copyright © Cengage Learning. All rights reserved
74
Section 21.7
The Biological Importance
of Coordination Complexes
Biological Importance of Iron
 Plays a central role in almost all living cells.
 Component of hemoglobin and myoglobin.
 Involved in the electron-transport chain.
Copyright © Cengage Learning. All rights reserved
75
Section 21.7
The Biological Importance
of Coordination Complexes
The Heme Complex
Section 21.7
The Biological Importance
of Coordination Complexes
Myoglobin


The Fe2+ ion is coordinated
to four nitrogen atoms in
the porphyrin of the heme
(the disk in the figure) and
on nitrogen from the
protein chain.
This leaves a 6th
coordination position (the
W) available for an oxygen
molecule.
Section 21.7
The Biological Importance
of Coordination Complexes
Hemoglobin


Each hemoglobin has two
α chains and two β
chains, each with a heme
complex near the center.
Each hemoglobin
molecule can complex
with four O2 molecules.
Copyright © Cengage Learning. All rights reserved
78
Section 21.8
Metallurgy and Iron and Steel Production
Metallurgy
 Process of separating a metal from its ore and
preparing it for use.
 Steps:
 Mining
 Pretreatment of the ore
 Reduction to the free metal
 Purification of the metal (refining)
 Alloying
Copyright © Cengage Learning. All rights reserved
79
Section 21.8
Metallurgy and Iron and Steel Production
The Blast Furnace Used
In the Production of Iron
Copyright © Cengage Learning. All rights reserved
Section 21.8
Metallurgy and Iron and Steel Production
A Schematic of the Open Hearth Process for Steelmaking
CaCO3 
 CaO + CO2
Heat
4Al + 3O2 
 2Al2O3
Copyright © Cengage Learning. All rights reserved
81
Section 21.8
Metallurgy and Iron and Steel Production
The Basic Oxygen Process for Steelmaking
 Much faster.
 Exothermic oxidation
reactions proceed so
rapidly that they produce
enough heat to raise the
temperature nearly to the
boiling point of iron
without an external heat
source.