Bonding models: Discrete molecules

26 Jul 2018

General Chemistry Collection for New Faculty

Submitted by Kari Stone, Benedictine University

VIPEr to the rescue!

The first year as a faculty member is extremely stressful and getting through each class day to day is a challenge. This collection was developed with new faculty teaching general chemistry in mind pulling together resources on the VIPEr site to refer back to as the semester drags along. There are some nice in-class activities, lab experiments, literature discussions, and problem sets for use in the general chemistry course. There are also some nice videos and graphics that could be used to spark interest in your students.

Subdiscipline: 
Prerequisites: 
Corequisites: 
Course Level: 
25 Jun 2018

Orbital Overlap and Interactions

Submitted by Jocelyn Pineda Lanorio, Illinois College
Evaluation Methods: 

Evaluation was conducted by the instructor walking around the computer lab to check progress and address the issues students had.

Evaluation Results: 

This LO was implemented once in advanced inorganic chemistry composed of 5 chemistry major students. Students clearly identified the type of orbital interactions and differentiated bonding, nonbonding, and antibonding MOs. Students commented that this is a great in-class activity before the discussion of MOs for diatomic molecules (Chapter 5 of MFT).

Description: 

This is a simple in-class activity that asks students to utilize any of the given available online orbital viewers to help them identify atomic orbital overlap and interactions. 

Learning Goals: 

Following the activity, students will be able to:

  1. draw the s, p, and d atomic orbitals using the given coordinate axes
  2. analyze the orbital interaction by looking at their symmetry and overlap (or lack of)
  3. differentiate s, p, d, and nonbonding molecular orbital

 

Equipment needs: 

Internet connection and computer

Prerequisites: 
Corequisites: 
Implementation Notes: 

This activity should be run in a computer lab.

Time Required: 
15 to 20 minutes
23 Jun 2018
Evaluation Methods: 

 A key is provided for the discussion questions. The discussion questions can be collected and graded.

Description: 

The activity is designed to be a literature discussion based on Nicolai Lehnert's Inorganic Chemistry paper, Mechanism of N-N Bond Formation by Transition Metal-Nitrosyl Complexes: Modeling Flavodiiron Nitric Oxide Reductases.  The discussion questions are designed for an advanced level inorganic course. 

 

Corequisites: 
Course Level: 
Learning Goals: 

Upon completion of this activity, students will be able to:

  1. Identify the overall research goal(s) of the paper.

  2. Define and identify non-innocent ligands.

  3. Identify how electron density on the metal center can impact ligand coordination.

  4. Draw molecular orbital diagrams for coordination compounds.

  5. Identify covalency by interpreting molecular orbital diagrams and data.

  6. Define and interpret Enemark-Feltham notation.

  7. Recognize spin multiplicity of the metal and ligand fragments in a complex and how it corresponds to the overall spin multiplicity.

  8. Identify possible electronic structures of {FeNO} complexes.

  9. Describe various characteristics to be considered in the selection of a good reductant.

  10. Explain how occupying bonding versus antibonding orbitals changes the reactivity of a system.

Implementation Notes: 

This is a very involved article with lots of great concepts. It will take a lot of time to read. We suggest giving this as a student group assignment. Give the students a copy of the article and discussion questions. Give them 1-2 weeks to read through the article and complete the discussion questions. Spend one or two 50 min. class periods going over the discussion questions. 

Note: This was developed during the 2018 VIPEr Workshop and has not been implemented, yet. Above instructions are an initial guide, any feedback is welcome and appreciated!

Time Required: 
50-90 min.
23 Jun 2018

Bonding in Tetrahedral Tellurate (updated and expanded)

Submitted by Jocelyn Pineda Lanorio, Illinois College
Evaluation Results: 

This LO was developed for the Summer 2018 VIPEr workshop, and has not yet been implemented. Results will be updated after implementation.

Description: 

This literature discussion is an expansion of a previous LO (https://www.ionicviper.org/literature-discussion/tetrahedral-tellurate) and based on  a 2008 Inorganic Chemistry article http://dx.doi.org/10.1021/ic701578p

Corequisites: 
Prerequisites: 
Learning Goals: 

Upon completion of this activity, students will be able to:

  1. Identify the key aspects of a primary publication including significance, synthetic methods, and product characterization.
  1. Identify isoelectronic species by drawing Lewis Structures.  
  1. Apply standard NMR shielding/deshielding concepts to interpret heteronuclear NMR spectra.
  1. Identify experimental protocols and reaction conditions.
  1. Discuss how the various experimental methods in the article provide evidence of the structure of the compound.
  1. Recognize scientific nomenclature relevant to the research article.
  1. Identify the relationship of telluric acid and tellurate to the related species given in the paper based on periodic trends. (Periodic Acid - isoelectronic; Sulfuric and Selenic acid - same column)
  1. Compare bond lengths for species in the paper.
  1. Identify the point group of the TeO42- with all the same Te-O bond lengths and when with different Te-O bond lengths.
  1. Predict the product(s) and by-products of a chemical reaction.
  1. Identify species and intermolecular interactions in a crystal structure.

 

Related activities: 
Implementation Notes: 

Students are asked to read the paper and answer the discussion questions before coming to class. 

Time Required: 
50 +
22 Jun 2018
Evaluation Methods: 

An answer key is included for faculty.

Evaluation Results: 

This LO was developed for the summer 2018 VIPEr workshop, and has not yet been implemented.  Results will be updated after implementation.

Description: 

This acitivty is a foundation level discussion of the Nicolai Lehnert paper, "Mechanism of N-N Bond Formation by Transition Metal-Nitrosyl Complexes: Modeling Flavodiiron Nitric Oxide Reductases".  Its focus lies in discussing MO theory as it relates to Lewis structures, as well as an analysis of the strucutre of a literature paper.

Prerequisites: 
Corequisites: 
Course Level: 
Learning Goals: 

Upon completion of this activity, students will be able to:

  1. Write a balanced half reaction for the conversion of NO to N2O and analyze a reaction in terms of bonds broken and bonds formed.

  2. Evaluate the structures of metal complexes to identify coordination number, geometry (reasonable suggestion), ligand denticity, and d-electron count in free FeII/FeIII centers.

  3. Recognize spin multiplicity of metal centers and ligand fragments in a complex.

  4. Interpret a reaction pathway and compare the energy requirements for each step in the reaction.

  5. Draw multiple possible Lewis Structures and use formal charges to determine the best structure.

  6. Draw molecular orbital diagrams for diatomic molecules.

  7. Identify the differences in bonding theories (Lewis vs MO), and be able to discuss the strengths and weaknesses of each.

  8. Interpret calculated MO images as σ or π bonds.

  9. Identify bond covalency by interpreting molecular orbital diagrams and data.

  10. Define key technical terms used in an article.

  11. Analyze the structure of a well written abstract.

  12. Identify the overall research goal(s) of the paper.

  13. Discuss the purposes of the different sections of a scientific paper.

Implementation Notes: 

The paper in which this discussion is centered around is very rich in concepts, and will take time for students to digest.  As the technical level is higher than most foundation level course, it is strongly recommended that students focus on the structure of the paper, and not the read the entire paper.  The discussion is modular with focuses on both MO theory drawn form the paper, as well as a general anatomy of how literature papers are organized and what constitutes a good abstract.  Either focus could take a single 50 minute lecture, with two being necessary to complete both aspects.  Instructors can choose either focus, or both depending on their course learning goals.

This was developed during the 2018 VIPEr workshop and has not yet been implemented.  The above instructions are a guide and any feedback is welcome and appreciated!

Time Required: 
One or two 50 minute lectures depending on instructor's desired focus
22 Jun 2018
Evaluation Methods: 

Discuss students responses with respect to the answer key.

Evaluation Results: 

This activty was developed for the IONiC VIPEr summer 2018 workshop, and has not yet been implemented.

Description: 

Inorganic chemists often use IR spectroscopy to evaluate bond order of ligands, and as a means of determining the electronic properties of metal fragments.  Students can often be confused over what shifts in IR frequencies imply, and how to properly evaluate the information that IR spectroscopy provides in compound characterization.  In this class activity, students are initially introduced to IR stretches using simple spring-mass systems. They are then asked to translate these visible models to molecular systems (NO in particular), and predict and calculate how these stretches change with mass (isotope effects, 14N vs 15N).  Students are then asked to identify the IR stretch of a related molecule, N2O, and predict whether the stretch provided is the new N≡N triple bond or a highly shifted N-O single bond stretch.  Students are lastly asked to generalize how stretching frequencies and bond orders are related based on their results.

 
Learning Goals: 
  1. Evaluate the effect of changes in mass on a harmonic oscillator by assembling and observing a simple spring-mass system (Q1 and 2)

  2. Apply these mass-frequency observations to NO and predict IR isotopic shift (14N vs. 15N) (Q3 and 4)

  3. Predict the identity of the diagnostic IR stretches in small inorganic molecules. (Q5, 6, and 7)

Equipment needs: 

Springs, rings, stands, and masses (100 and 200 gram weights for example).

 

Corequisites: 
Implementation Notes: 

Assemble students into small groups discussions to answer the questions to the activity and collaborate.

 

 

Time Required: 
Approximately 50 minutes
1 Jun 2018
Evaluation Methods: 

This LO has not been implemented; however, we recommend a few options for evaluating student learning:

  • implement as in-class group work, collect and grade all questions

  • have students complete the literature discussion questions before lecture, then ask them to modify their answers in another pen color as the in-class discussion goes through each questions

  • hold a discussion lecture for the literature questions; then for the following lecture period begin class with a quiz that uses a slightly modified problem.

Evaluation Results: 

This LO has not been implemented yet.

Description: 

In honor of Professor Richard Andersen’s 75th birthday, a small group of IONiC leaders submitted a paper to a special issue of Dalton Transactions about Andersen’s love of teaching with the chemical literature. To accompany the paper, this literature discussion learning object, based on one of Andersen’s recent publications in Dalton, was created. The paper examines an ytterbium-catalyzed isomerization reaction. It uses experimental and computational evidence to support a proton-transfer to a cyclopentadienyl ring mechanism versus an electron-transfer mechanism, which might have seemed more likely.

 

The paper is quite complex, but this learning object focuses on simpler ideas like electron counting and reaction coordinate diagrams. To aid beginning students, we have found it helpful to highlight the parts of the paper that relate to the reading questions. For copyright reasons, we cannot provide the highlighted paper here, but we have included instructions on which sections to highlight if you wish to do that.

 

Corequisites: 
Course Level: 
Learning Goals: 

After completing this literature discussion, students should be able to

  • Count the valence electrons in a lanthanide complex

  • Explain the difference between a stoichiometric and catalytic reaction

  • Predict common alkaline earth and lanthanide oxidation states based on ground state electron configurations  

  • Describe how negative evidence can be used to support or contradict a hypothesis   

  • Describe the energy changes involved in making and breaking bonds

  • On a reaction coordinate diagram, explain the difference between an intermediate and a transition state

  • Explain how calculated reaction coordinate energy diagrams can be used to make mechanistic arguments

Implementation Notes: 

This is a paper that is rich in detail and material. As such, an undergraduate might find it intimidating to pick up and read. We have provided a suggested reading guide that presents certain sections of the paper for the students to read. We suggest the instructor highlight the following sections before providing the paper to the students. While students are certainly encouraged to read the entire paper, this LO will focus on the highlighted sections.  

 

Introduction

            Paragraph 1

            Paragraph 2

            Paragraph 3

            Paragraph 4

First 5 lines ending at the word high (you may encourage students to look up exergonic if that is not a term commonly used in your department)

Line 14 starting with “In that sense,” through the end of the paragraph

            Paragraph 6

From the start through the word “endoergic” in line 22

Line 31 from “oxidation of” to the word “described” in line 33

Line 40 from “These” to the word “dimethylacetylene” in line 45

Paragraph 7

            From the start to the word “appears” in line 4

            The words “to involve” in line 4

            Starting in line 4 with “a Cp*” to “transfer” in line 5

Results and Discussion

            Paragraph 1

            Paragraph 2

            Paragraph 3 from the start through “six hours” in line 10

            Paragraph 4

            Paragraph 5

                        From the start to “solution” in line 3

                        From “This exchange” in line 10 to “allene” in line 11

                        From “Hence” in line 19 through the end of the paragraph

            Paragraph 6 from the start through “infrared spectra” in line 19

            Paragraph 7 from “Hence” in line 4 through the end of the paragraph

Mechanistic aspects for the catalytic isomerisation reaction of buta-1,2-diene to but-2-yne using (Me5C5)2Yb p 2579.

            Paragraph 1

            Paragraph 2

            Paragraph 3

            Paragraph 4

Experimental Section

            Synthesis of (Me5C5)2Yb(η2-MeC≡CMe).

            Synthesis of (Me5C5)2Ca(η2-MeC≡CMe).

Reaction of (Me5C5)2Yb with buta-1,2-diene

 

 

 

Time Required: 
One class period.
14 Aug 2017

Chapter 10--Stanley Organometallics

Submitted by George G. Stanley, Louisiana State University
Description: 

Chapter 10 from George Stanley's organometallics course, M-M bonding

 

this chapter covers bonding and structure of metal-metal bonds and some descriptive chemistry.

The powerpoint slides contain answers to some of the in-class exercises, so those are behind the "faculty only" wall. I share these with students after the class, but not before.

Everyone is more than welcome to edit the materials to suit their own uses, and I would appreciate being notified of any mistakes that are found.


Subdiscipline: 
Corequisites: 
Course Level: 

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