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CHEM202: Advanced Inorganic Chemistry

Unit 3: Transition Metals   Transition metals differ from s- and p-block metals because electrons in the d orbitals are available for coordination and bonding.  Each atom has a total of 5 d orbitals, accommodating up to 10 electrons total.  In a metal complex, these d orbitals do not possess the same energy as they do in single isolated atoms; rather, they have different energies that are determined by their specific molecular geometry and their coordinated ligands.  Electrons populate the low energy d orbitals first; however, these electrons can be easily excited from a low energy d orbital to a higher energy d orbital (a process known as “electronic excitation”) or can be easily removed from the metal complex (a process known as “ionization”).  The physical/chemical behavior and reactivity of a transition metal depend strongly on the number of d-electrons in the molecule.  In this unit, you will learn how d orbitals are organized in a metal complex and how electrons populate these orbitals.  The resulting electronic structure of the transition metal complexes determines properties such as magnetism and color.   

Unit 3 Time Advisory
This unit should take you approximately 26 hours to complete.

☐    Subunit 3.1: 1.0 hour

☐    Subunit 3.2: 2.0 hours

☐    Subunit 3.3: 2.5 hours

☐    Subunit 3.4: 1.5 hours

☐    Subunit 3.5: 4.0 hours

☐    Subunit 3.6: 1.0 hour

☐    Subunit 3.7: 9.0 hours
 

☐    Introduction: 3.0 hours
 

☐    Sub-subunit 3.7.1: 1.0 hour

☐    Sub-subunit 3.7.2: 1.0 hour

☐    Sub-subunit 3.7.3: 2.0 hours

☐    Sub-subunit 3.7.4: 1.0 hour

☐    Sub-subunit 3.7.5: 1.0 hour
 

☐    Subunit 3.8: 5 hours

Unit3 Learning Outcomes
Upon successful completion of this unit, the student will be able to: - Predict molecular structures using valence shell electron pair repulsion (VSEPR) theory and account for distortions from “ideal” geometries (Jahn-Teller distortions). - List physical and chemical properties of transition metals. - Name transition metal complexes according to IUPAC standards and identify (and name) structural and stereo isomers of these compounds. - Identify proper electronic configurations and electron counts of d-block metals, as well as explain their stable oxidation states. - Compare and contrast valence bond theory and molecular orbital theory. - Use the spectrochemical series to determine spectroscopic behavior and ligand substitutions. - Explain crystal field theory and how it accounts for physical and chemical properties such as color and magnetism. - Use ligand field theory to decribe molecular bonding and the chemical/physical properties of transition metal complexes.

3.1 Physical Properties   - Reading: UC Davis: ChemWiki’s “Periodic Trends” Link: UC Davis: ChemWiki’s “Periodic Trends” (HTML)
 
Instructions: Please read the entire webpage and work through the six questions found at the end of the reading.  This material covers the basic periodic trends of d-block transition metals.  
  
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3.2 VSEPR Structures of Transition Metals   - Reading: UC Davis: ChemWiki’s “Molecular Geometry” Link: UC Davis: ChemWiki’s “Molecular Geometry” (HTML)
 
Instructions: Please read the entire webpage.  This material describes valence shell electron pair repulsion and how it gives rise to molecular geometries.  Please also click on the individual geometries of the molecules for a more thorough explanation of each.     
 
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3.3 Nomenclature of Transition Metal Complexes   - Lecture: MIT: Principles of Chemical Science, Fall 2008: “Lecture 27: Transition Metals” Link: MIT: Principles of Chemical Science, Fall 2008: “Lecture 27: Transition Metals” (Adobe Flash, Mp4, or iTunes)
 
Also available in:
YouTube
 
Instructions: Please watch the lecture, starting around 9:30 (total runtime = 45:07 minutes).  This material covers the introductory material about d-block transition metals, including nomenclature and electron counting.
 
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  • Reading: University of Rhode Island’s “Chemistry 401 Nomenclature of Transition Metal Complexes” Link: University of Rhode Island’s “Chemistry 401 Nomenclature of Transition Metal Complexes” (HTML)
     
    Instructions: Please read the entire webpage and work through the given examples.  The only way to become fluent in nomenclature is practice!  This material covers naming transition metal complexes, first addressing the cationic and neutral molecules, then covering the anionic molecules. 
     
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  • Reading: Purdue University: George M. Bodner’s “Nomenclature of Complexes” Link: Purdue University: George M. Bodner’s “Nomenclature of Complexes” (HTML)
     
    Instructions: Please read the entire webpage and work the five review problems at the bottom.  The only way to become fluent in nomenclature is practice!  This material summarizes the naming process of transition metal complexes. 
     
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3.4 Isomers of Transition Metal Complexes   - Reading: University of the West Indies: Robert J. Lancashire’s “Isomerism in Coordination Compounds” Link: University of the West Indies: Robert J. Lancashire’s “Isomerism in Coordination Compounds” (HTML)
 
Instructions: Please read the entire webpage.  This material covers several types of isomers of transition metal complexes.  It is important to note which are structural isomers and which are stereoisomers. 
 
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  • Reading: Purdue University: George M. Bodner’s “Isomers” Link: Purdue University: George M. Bodner’s “Isomers” (HTML)
     
    Instructions: Please read the entire webpage.  The images in this material are helpful in remembering the different types of isomers and their subsequent naming. 
     
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3.5 Electron Configurations of Transition Metals   - Reading: Purdue University: George M. Bodner’s “Transition Metals” Link: Purdue University: George M. Bodner’s “Transition Metals” (HTML)
 
Instructions: Please read the entire webpage and work through the practice problem.  This material familiarizes you with the electron configuration of transition metals and introduces oxidation states, which will be further discussed in sub-subunit 3.5.2.   
 
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3.5.1 Eighteen Electron Rule   - Reading: Rob Toreki’s Organometallic HyperTextBook: “The 18 Electron Rule” Link: Rob Toreki’s Organometallic HyperTextBook: “The 18 Electron Rule” (HTML)
 
Instructions: Please read the entire webpage.  Also work the 10 self-test problems at the bottom of the page.  This material introduces the two main methods of counting electrons.  Both will give you the correct answer if executed properly.  You may choose which one you wish to use, or attempt both.  
 
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3.5.2 Oxidation States   - Reading: UC Davis: ChemWiki’s “Oxidation States of Transition Metals” Link: UC Davis: ChemWiki’s “Oxidation States of Transition Metals” (HTML)
 
Instructions: Please read the entire webpage.  This material describes the multiple oxidation states of transition metals and how electrons are lost from the full valence.  Please be aware that Co and Cr have unique electron filling in their highest s orbitals.  The external links at the bottom of the page show how to approach these types of problems stepwise and are an invaluable learning tool.    
 
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3.6 Valence Bond Theory   - Reading: Purdue University: George M. Bodner’s “The Valence-Bond Approach to Bonding in Complexes” Link: Purdue University: George M. Bodner’s “The Valence-Bond Approach to Bonding in Complexes” (HTML)
 
Instructions: Please read the entire webpage and work through the practice problem.  This material describes how electron configurations can be used to describe bonding in metal complexes.
 
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3.7 Crystal Field Theory   - Lecture: MIT: Principles of Chemical Science, Fall 2008: “Lecture 28: Crystal Field Theory” Link: MIT: Principles of Chemical Science, Fall 2008: “Lecture 28: Crystal Field Theory” (Adobe Flash, Mp4, or iTunes)
 
Also available in:
YouTube
 
Instructions: Please watch the lecture (runtime = 45:24 minutes).  This material covers crystal field theory.
 
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  • Reading: UC Davis: ChemWiki’s “Crystal Field Theory” Link: UC Davis: ChemWiki’s “Crystal Field Theory” (HTML or PDF)
     
    Instructions: Please read the entire webpage.  This material introduces the idea of splitting within the orbitals.  This phenomenon gives rise to color and magnetic properties of complexes.  Please also work the five problems at the end of the reading.  The answers can be found at the bottom of the page of files by clicking on the “answers” link.  They are referenced by molecular geometry and spin type. You may access the PDF version of this page by clicking the “Make PDF” button on the link above. 
     
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  • Reading: Purdue University: George M. Bodner’s “Crystal Field Theory” Link: Purdue University: George M. Bodner’s “Crystal Field Theory” (HTML)
     
    Instructions: Please read the entire webpage and work through the practice problem.  This material describes the splitting of orbital energy levels in crystal field theory.  Please notice that the molecular geometry of the molecule and the nature of the ligand play important roles in the electronic configurations.
     
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3.7.1 Spectrochemical Series   - Reading: UC Davis: ChemWiki’s “Spectrochemical Series” Link: UC Davis: ChemWiki’s “Spectrochemical Series” (HTML)
 
Instructions: Please read the entire webpage.  This material discusses the spectrochemical series, or the influence of the ligands on orbital splitting.  The sigma and pi orbital interactions are also discussed.
 
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3.7.2 Crystal-Field Splitting Parameter   - Reading: UC Davis: ChemWiki’s “Energy Level Splitting” Link: UC Davis: ChemWiki’s “Energy Level Splitting” (HTML)
 
Instructions: Please read the entire webpage.  This material focuses on the splitting of energy levels and the spectroscopic implications that arise from it.  This information helps explain why a ruby is red while an emerald is green.
 
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3.7.3 High Spin/Low Spin Complexes   - Reading: UC Davis: ChemWiki’s “High Spin and Low Spin” Link: UC Davis: ChemWiki’s “High Spin and Low Spin” (HTML)

 Instructions: Please read the entire webpage.  This information
allows you to determine whether a complex will be high spin or low
spin, which is critical in predicting its spectroscopic and magnetic
behavior.  Work through the four examples in the text and then the
six questions at the end of the reading.   
    
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webpage above.

3.7.4 Magnetism   - Reading: UC Davis: ChemWiki’s “Magnetic Properties of Coordination Complexes” Link: UC Davis: ChemWiki’s “Magnetic Properties of Coordination Complexes” (HTML)
 
Instructions: Please read the entire webpage.  This information discusses magnetism, focusing on paramagnetism and how the electron configuration causes a complex to react to a magnetic field.
 
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3.7.5 Jahn-Teller Distortions   - Reading: University of Rhode Island’s “Chemistry 401: Thermodynamics, Geometries Other Than Octahedral, Jahn-Teller” Link: University of Rhode Island’s “Chemistry 401: Thermodynamics, Geometries Other Than Octahedral, Jahn-Teller” (HTML)
 
Instructions: Please read the entire webpage.  This material describes how changes in molecular geometry affect the stability of a complex.  When this occurs through slight distortions from “true” geometries, it is referred to as a Jahn-Teller distortion. Note that LFSE stands for ligand field stabilization energy and is also a measure of stability. 
 
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3.8 Ligand Field Theory   - Reading: Purdue University: George M. Bodner’s “Ligand Field Theory” Link: Purdue University: George M. Bodner’s “Ligand Field Theory” (HTML)
 
Instructions: Please read the entire webpage.  This material describes a third theory to explain the bonding and properties of coordination complexes.
 
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3.8.1 Sigma Bonding   - Reading: UC Davis: ChemWiki’s “Sigma Bonding” Link: UC Davis: ChemWiki’s “Sigma Bonding”  (HTML)
 
Also available in:
PDF                                                                             
 
Instructions: Please read the entire webpage.  This material summarizes ligand-field theory and provides an interactive visual representation of a sigma bond between Cr and CO.  
 
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3.8.2 Pi Bonding   - Reading: UC Davis: ChemWiki’s “Pi Bonding in Coordination Compounds” Link: UC Davis: ChemWiki’s “Pi Bonding in Coordination Compounds” (HTML)
 
Also available in:
PDF
 
Instructions: Please read the entire webpage.  This material provides an interactive visual representation of the pi interaction between Cr and CO.  
 
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  • Assessment: University of Rhode Island’s “Chemistry 401: d-Metal Complexes Practice Problems” Link: University of Rhode Island’s “Chemistry 401: d-Metal Complexes Practice Problems” (HTML)
     
    Instructions: Please work through problems 1–11.  The answers are provided by clicking on the links at the end of each question.
     
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