1. Transition Metals and Coordination Chemistry
Chapter 21
Transition Metals and Coordination Chemistry

2. 21.1 The Transition Metals: A Survey
The First-Row Transition Metals
Coordination Compounds
21.4 Isomerism
21.5 Bonding in Complex Ions: The Localized Electron Model
21.6 The Crystal Field Model
21.7 The Biologic Importance of Coordination Complexes
21.8 Metallurgy and Iron and Steel Production
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3. 20.1 The Transition Metals - I
Industry : Fe , Cu , Ti , Ag ,  table 21.1
Biosystem : transport , storage , catalyst , 
20.1 The Transition Metals - I

4. Transition Metals
Show great similarities within a given period as well as within a given vertical group.
(1) General Properties ( Sc → Cu )
a) Great similarities within a period as well as a group
∵ d subshells incomplerely filled.
 distinctive coloring
 formation of paramagnetic compounds
 catalytic behavior
 tendency to form complex ions.
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6. Cations are often complex ions – species where the transition metal ion is surrounded by a certain number of ligands (Lewis bases). The Complex Ion Co(NH3)63+ :
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7. (2) Electron configurations : 4s before 3d ( Cr / Cu )
b) difference :
m.p : W / Hg
Hard / soft : Fe , Ti / Cu , Au , Ag
Reactivity & oxides : Cu / Fe ; Fe2O3 / CrO3
(2) Electron configurations : 4s before 3d
( Cr / Cu )
Table 21.2 p.931
(3) Oxidation states
most common : +2 , +3 ( +2 ～ +7 )
more than one oxidation states

9. (4) Ionization energies
(5) Reduction Potentials
─────→ period， reducing ability ↓ ( Zn , Cr )
∵ Zeff ↑  r ↓ ; IE ↑

10. 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
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11. 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
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12. └→ colored & paramagnetic (often)
consists of a complex ion
Coordination compounds are neutral species in which a small number of molecules or ions surround a central metal atom or ion.
ex.
[Co(NH3)5Cl]Cl2
complex ion : [Co(NH3)5Cl]2+

13. ionic force counter ions central metal ligands complex ion
coordinate covalent bond
Complex ion = metal cation ligands
e acceptor e donor
center (one) surrounding (  2 )
transion metal
Lewis acid Lewis base
[ Co(NH3)5Cl ]Cl2
H2O , NH3 , :Cl－ ..
ionic force
counter ions
central metal ligands
complex ion

14. (2) Coordination number :
The # of donor atoms surrounding the central metal
The most common : 4 or 6

15.  Chelating agents (3) Ligands :
A neutral molecule or ion having a line pair that can be used to from a bond to a metal ion.
monodentate : H2O, NH3
bidentate : en , ox
polydentate : EDTA
 Chelating agents

16. p. 939, Table 21-13

17. Rules for naming coordination compounds : p.940  oxidation number :
(4) Nomenclature :
Rules for naming coordination compounds : p.940
 oxidation number :
Net charge = charges on (central metal + ligands)
[ PtCl6]2－ [Cu(NH3)4]2＋
└→ └→ +2
ex. (a) [Co(NH3)5Cl]Cl2
Pentaammine chloro cobalt(III) chloride
cation anion

18. p. 940, Table 21-14

19. (4) Nomenclature : ex. (b) K3[Fe(CN)6] ex. (c) [Fe(en)2(NO2) 2]2SO4
potassium hexacyanoferrate (III)
cation anion
ex. (c) [Fe(en)2(NO2) 2]2SO4
bis (ethylenediamine) dinitro iron(III) sulfate
cation anion

20. hexaaquacobalt(III) bromide sodiumtetrachloro-platinate(II)
Exercise
Name the following coordination compounds.
[Co(H2O)6]Br3
Na2[PtCl4]
hexaaquacobalt(III) bromide
sodiumtetrachloro-platinate(II)
a) hexaaquacobalt(III) bromide
b) sodiumtetrachloro-platinate(II)
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22. Coordination Isomerism: Composition of the complex ion varies.
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.
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23. Linkage Isomerism of NO2–
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24. Geometrical Isomerism (cis-trans):
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)
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25. Geometrical (cis-trans) Isomerism for a Square Planar Compound a) cis isomer b) trans isomer
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26. Geometrical (cis-trans) Isomerism for an Octahedral Complex Ion
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27. Isomers have opposite effects on plane-polarized light.
Stereoisomerism
Optical Isomerism:
Isomers have opposite effects on plane-polarized light.
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28. Enantiomers – isomers of nonsuperimposable mirror images.
Optical Activity
Exhibited by molecules that have nonsuperimposable mirror images (chiral molecules).
Enantiomers – isomers of nonsuperimposable mirror images.
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29. p. 947, Fig

31. Ex at p 948
p. 948, Fig

32. Does [Co(en)2Cl2]Cl exhibit geometrical isomerism? Yes
Concept Check
Does [Co(en)2Cl2]Cl exhibit geometrical isomerism?
Yes
Does it exhibit optical isomerism?
Trans form – No
Cis form – Yes
Explain.
See Figure [Co(en)2Cl2]Cl exhibits geometrical isomerism (trans and cis forms). The trans form does not exhibit optical isomerism but the cis form does exhibit optical isomerism.
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33. Bonding in Complex Ions
The VSEPR model for predicting structure generally does not work for complex ions.
However, assume a complex ion with a coordination number of 6 : octahedral
two ligands : linear.
a coordination number of 4 : tetrahedral or square planar.
The interaction between a metal ion and a ligand : Lewis acid–base reaction
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34. Hybrid Orbitals for 6,4, and 2 ligands
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35. Focuses on the energies of the d orbitals. Assumptions
Ligands are negative point charges.
Metal–ligand bonding is entirely ionic:
strong-field (low–spin):
large splitting of d orbitals
weak-field (high–spin):
small splitting of d orbitals
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36. Two types of electrostatic forces :
Explains the bonding in complex ions solely in terms of electrostatic forces.
Two types of electrostatic forces :
attraction : ( M＋ ) & ( ligand ion － or ligand ： )
repulsion : ( ligand ： ) & ( metal e in d orbitals )
Consider : octahedral complexes
● ●
● ● ●
● ● ● ● ● D

37. An Octahedral Arrangement of Point-Charge Ligands and the Orientation of the 3d Orbitals
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38. The Energies of the 3d Orbitals for a Metal Ion in an Octahedral Complex
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39. Strong–field (low–spin): Weak–field (high–spin):
Possible Electron Arrangements in the Split 3d Orbitals in an Octahedral Complex of Co3+
Strong–field (low–spin):
Yields the minimum number of unpaired electrons.
Weak–field (high–spin):
Gives the maximum number of unpaired electrons.
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40. Spectrochemical Series
a list of ligands arranged in order of their abilities to split the d orbital energies
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.
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41. Color : arise when complexes absorb light in some
Color : arise when complexes absorb light in some portion of the visible spectrum. (Table 21.16)
ex. [Cu(H2O)6]2+ → blue D = E = hn

42. ex. [Ti(H2O)6]3+ max absorption at 498 nm

43. color of gems
p. 954, Table 21-17

44. Concept Check
Which of the following are expected to form colorless octahedral compounds? 
Zn2+ Fe2+ Mn2+
Cu+ Cr3+ Ti Ag+
Fe3+ Cu2+ Ni2+
There are 4 colorless octahedral compounds. These are either d10 ions (Zn2+, Cu+, Ag+), or the d0 ion (Ti4+). If electrons cannot move from one energy level to the next in the energy level diagram, there is no color absorbed.
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45. 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.
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46. The d Orbitals in a Tetrahedral Arrangement of Point Charges
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47. The Crystal Field Diagrams for Octahedral and Tetrahedral Complexes
Difference in energy between the split d orbitals is significantly less,
Weak–field case (high–spin) always applies for.
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48. Consider the Crystal Field Model (CFM).
Concept Check
Consider the Crystal Field Model (CFM).
Which is lower in energy, d–orbital lobes pointing toward ligands or between? Why?
The electrons in the d–orbitals – are they from the metal or the ligands?
In all cases these answers explain the crystal field model. The molecular orbital model is a more powerful model and explains things differently. However, it is more complicated. This is another good time to discuss the role of models in science.
a) Lobes pointing between ligands are lower in energy because we assume ligands are negative point charges. Thus, orbitals (with electron probability) pointing at negative point charges will be relatively high in energy.
b) The electrons are from the metal.
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49. 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. 
Ni(NH3)62+
Fe(CN)63–
Co(NH3)63+
a) A d 8 ion will look the same as strong field or weak field in an octahedral complex. In each case there are two unpaired electrons.
b) This is a d 5 ion. In the weak field case, all five electrons are unpaired. In the strong field case, there is one unpaired electron.
c) This is a d 6 ion. In the weak field case, there are four unpaired electrons. In the strong field case, there are no unpaired electrons.
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50. What are some possible metal ions for which this would be true?
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+.
Metal ions would need to be d4 or d7 ions. Examples include Mn3+, Co2+, and Cr2+.
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51. Concept Check
Between [Mn(CN)6]3– and [Mn(CN)6]4– which is more likely to be high spin? Why?
[Mn(CN)6]4- is more likely to be high spin because the charge on the Mn ion is 2+ while the charge on the Mn ion is 3+ in the other complex. With a larger charge, there is bigger splitting between energy levels, meaning strong field, or low spin.
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52. The d Energy Diagrams for Square Planar Complexes
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53. The d Energy Diagrams for Linear Complexes Where the Ligands Lie Along the z Axis
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54. Metal ion complexes are used in humans for the transport and storage of oxygen, as electron-transfer agents, as catalysts, and as drugs.
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55. First-Row Transition Metals and Their Biological Significance
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56. Biological Importance of Iron
Plays a central role in almost all living cells.
Component of hemoglobin and myoglobin.
Involved in the electron-transport chain.
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57. The Heme Complex
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58. 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.
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59. two α chains and two β chains complex with four O2 molecules.
Hemoglobin
two α chains and two β chains
complex with four O2 molecules.
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60. Hb(aq) + 4O2(g) Hb(O2)4(aq)
About high altitude sickness
Hb(aq) + 4O2(g) Hb(O2)4(aq)
p. 959, Fig

61. About Supercharge Blood: EPO at page 960.
1964 Winter Olympics Gold medal’s winner
The 2009 Tour de France
p. 960, Fig