Physical Chemistry: Thermodynamics

1 Mar 2017

Reactivity and Bonding of Complexes with Metal-Metal Bonds

Submitted by S. Chantal E. Stieber, Cal Poly Pomona
Evaluation Methods: 

Evaluation was conducted by the instructor walking around the classroom and addressing individual problems students had.

Evaluation Results: 

From classroom observations, most students were able to properly count electrons and oxidation states for the metals in the complexes and rationalize the ligand coordination modes. Here, the main source of confusion was how to account for the Z-type Co-Zr interaction. The MO diagrams generated the most discussion and were the most difficult part for students (as was expected). The reactivity was also initially conceptually difficult for students, but once they realized how to treat the M-M bonded system, students were able to apply fundamental organometallic reactions to the system. Many students forgot what they had learned about magnetic moments in the previous quarter, but figured it out and were excited to apply knowledge from the previous course. 

Description: 

This problem set was designed to be an in-class activity for students to practice applying their knowledge of metal-metal bonding (as discussed in the previous lecture) to recently published complexes in the literature. In this activity, complexes from four papers by Christine M. Thomas and coworkers are examined to give students practice in electron counting (CBC method), drawing molecular orbitals, and fundamental organometallic reactions.

Corequisites: 
Course Level: 
Learning Goals: 

Following the activity, a student should be able to:

·      Determine electron counts and oxidation states of complexes with M-M bonds using CBC electron counting method

·      Draw molecular orbital diagrams for M-M bonds

·      Determine M-M bond order

·      Propose mechanisms for reactions at M-M centers

·      Apply fundamental inorganic chemistry to reports in the literature

Implementation Notes: 

This was implemented in the second quarter of advanced inorganic chemistry (4th year level) before the second midterm as an in-class group activity. The worksheet generated a lot of interest from the students and generated good discussions in a class of 23 students. In the previous lecture, we discussed basic metal-metal bonding, including drawing MO diagrams and determining bond order for homobimetallic complexes. This worksheet was a reasonable extension, requiring students to apply this knowledge to more complicated systems.

Time Required: 
65 min
28 Dec 2016

Isotope Effects in Arene C-H Bond Activation by Cp*Rh(PMe3)

Submitted by Adam R. Johnson, Harvey Mudd College
Evaluation Methods: 

This LO was used in class to help a student guide a discussion of the paper. We did not cover all of the LO in a 75 minute class period, as we let the discussion take us where it wanted to. 


A better way to ensure student preparation would be to collect the questions at the beginning (or end, if they wanted to use their notes in class) of class to ensure that they had really studied the paper.

Evaluation Results: 

I used this LO as a guided reading handout and did not collect the answers so I do not have any assessment data at this time.

Although my students found this paper to be relatively dense and hard to follow at times. The paper separates out the Results and Discussion sections, so at times it seems repetitive. However, once they had worked their way through the paper, the students found the results interesting and the methods informative. We were able to discuss it at a high level in class.

Description: 

This literature discussion is based on a paper by Bill Jones and Frank Feher (J. Am. Chem. Soc., 1986, 108, 4814-4819). In this paper, they study the activation of aromatic C-H bonds by a rhodium complex. Through careful experimental design, they were able to examine isotope effects on the selectivity of the reaction. Analysis of the rate data allowed them to prepare a reaction coordinate free energy diagram. This paper also introduces the effects of C-H bond breaking in early or late transition states on the vibrational energy spacing at both ground and excited states. The paper is a good way to bring kinetic isotope effects into the classroom. The paper also introduces the concept of deuterium labeling experiments and what that information can tell you.

An important aspect of this paper, and what makes it so interesting, is that they are able to get two kinetic isotope effects, one for each step of the reaction. From these two KIEs alone they are able to determine the unexpected rate-determining step of the reaction. It is a triumph of mechanistic investigation into intermediates that are undetectable.

This LO presents a series of guided reading questions that help a student approach and understand the material presented in the paper in a more thorough way. Part one is a guided inquiry that allows the students to derive and understand differing zero point energies for proteated and deuterated compounds. Part two guides students  through the results presented in the paper to help them better understand how experimental data can be used to understand the mechanism of a chemical reaction. There is more to the paper than kinetic isotope effects, but that is the focus I chose while developing it. The LO is suitable for junior or senior undergraduates in an organometallics course or unit within an inorganic course.

I would like to acknowledge Ryan Pakula and Joanne Redford from my Chem 165 course in 2008 who wrote early versions of some of the questions about vibrational states, and a careful critical read by Nancy Williams, who understands this stuff at a much deeper level than I do.

Course Level: 
Learning Goals: 

upon completing this LO students should be able to
:
1. calculate and interrelate reduced mass, vibrational frequency, force constant, and zero point energies for vibrational states of bonds
2. define kinetic isotope effects (normal, and inverse)
3. calculate/predict/estimate a normal and inverse KIE for a chemical reaction from IR data.
4. interpret and describe a reaction coordinate diagram for a chemical reaction
5. count and classify metal complexes using CBC method

Subdiscipline: 
Implementation Notes: 

I used this LO as a guided reading handout for a senior-level organometallics class. The questions and the paper were provided to the students a week in advance and the in-class activity was a student-led discussion of the paper.

Time Required: 
1 50-75 minute class period for discussion
27 Dec 2016

Energetics and mechanisms of reductive elimination from Pt(IV)

Submitted by Adam R. Johnson, Harvey Mudd College
Evaluation Methods: 

This LO was used in class to help a student guide a discussion of the paper. We did not cover all of the LO in a 75 minute class period, as we let the discussion take us where it wanted to.

A better way to ensure student preparation would be to collect the questions at the beginning (or end, if they wanted to use their notes in class) of class to ensure that they had really studied the paper.

Evaluation Results: 

I used this LO as a guided reading handout and did not collect the answers so I do not have any assessment data at this time.

My students found this paper to be highly readable and very clear. It is dense, with a lot of information presented, but once the students dove in, we were able to discuss it at a high level.

Description: 

This literature discussion is based on a paper by Karen Goldberg (J. Am. Chem. Soc., 1995, 117, 6889-6896). In this early paper by Goldberg, she studied the reductive elimination of ethane and methyl iodide from dppePtMe3I. The paper is well written, and approachable for undergraduates. It shows a real, interesting application of thermodynamic and kinetic methods to the study of a problem in mechanistic chemistry. The experimental details are complete, and this paper would serve as a good review of kinetics, thermodynamics, and organometallic reaction mechanisms. 


This LO presents a series of guided reading questions that help a student approach some of the material presented in the paper in a more thorough way. It asks students to derive equations and understand how experimental data can be combined into a reaction coordinate free energy diagram. The LO is suitable for junior or senior undergraduates in an organometallics course or unit within an inorganic course.

An update and correction was made to the LO in April 2018. Questions 7 and 8 in the learning object have students address the point of the differing M-C and M-I bonds. For the purposes of understanding what was written at the time, the questions are still valid, but the conclusions drawn in the paper about M-X bond strengths are not. For more information, see the "faculty only" file entitled "Goldberg Update 201804."

Course Level: 
Learning Goals: 

upon completing this LO students should be able to

1. demonstrate where thermodynamic parameters come from in a reaction coordinate free energy diagram

2. derive complex rate equations using the steady state approximation

3. describe the principle of microscopic reversibility

4. gain a deeper appreciation for the experimental methods (thermodynamic and kinetic) used in mechanistic chemistry

Subdiscipline: 
Implementation Notes: 

I used this LO as a guided reading handout for a senior-level organometallics class. The questions and the paper were provided to the students a week in advance and the in-class activity was a student-led discussion of the paper.

Time Required: 
one 50-75 minute class period
27 Jun 2016

Student Oral Presentations of a Communication from the Primary Literature

Submitted by Carmen Works, Sonoma State University
Evaluation Methods: 

see rubric that is attached 

Description: 

In the humanities it is common practice to read a piece of literature and discuss it.  This is also practiced in science and is the purpose of this exercise.  Each student is assigned a communication from the current  literature (inorganic, JACS, organometallics, J. Phys. Chem) and the student presents this paper to the class.  The class will also have the opportunity to read the article prior to the presentation, and I post each paper on my LMS page.  The presenter will be responsible for explaining the paper, and leading a critical discussion.  This is not an easy assignment since these papers are filled with chemical jargon, but an important part of their chemical education is to be able to tackle the literature.  In addition a lot of this jargon is covered during the semester.

  

 

Course Level: 
Learning Goals: 

·      Students will learn to read a paper from the primary literature

·      Students will learn to present the a paper from the primary literature

·      Students will learn to create a group discussion

·      Students will learn how to relate chemical jargon learned throughout the four years of chemistry to the literature

·      Students will learn how to answer exam questions from the primary literature

 

Implementation Notes: 

I hand out selected communications during the second week of class.  Students are allowed to swap papers. They have the entire semester to read the paper and prepare a talk but the talks are during the last 3 weeks of class.  Each student is give 25 min to present their paper to the class.  The assignment is graded using the attached rubric and is worth 15% of their final grade.  I selected about 7 exam questions for the final exam and ask students to answer 5 of these questions.  I try to structure the questions so that they don't have to "know" every paper.  I have attached an example of such a question.  

2 Jul 2015
Evaluation Methods: 

Students will be evaluated on preparation and participation using the attached evaluation form.

Evaluation Results: 

This is a new learning object created at the 2015 Summer VIPEr workshop and not yet been implemented. Results will be added by the creators after use in a class.

Description: 

This Learning Object involves reading a recent scientific journal article, answering questions relating to the content, and participating in a classroom discussion. The paper under review is “Regeneration of an Iridium (III) Complex Active for Alkane Dehydrogenation Using Molecular Oxygen,” Organometallics, 33, 1337-1340. DOI: /10.1021/om401241e). This paper presents a summary of results from experiments relating to important recent advances in organometallic chemistry, including alkane dehydrogenation and using as an oxidant to regenerate the active form of a catalyst.

 

Corequisites: 
Course Level: 
Learning Goals: 

After completing this literature discussion, students should be able to:

  • explain in 1-2 sentences the relevance/importance/rationale of a paper and what the conclusions are

  • interpret proton NMR spectra in the context of the paper

  • explain from the standpoint of the thermodynamic principles why the uphill transformation from alkane to alkene in this case is possible and non-reversible

  • count electrons in transition metal complexes and identify oxidation states and oxidized and reduced species
  • integrate their chemical knowledge and be able to come up with a reasonable answer to “what is the next step?” in the context of this paper

Implementation Notes: 

Give the hand out (or post the assignment online) to students ~1 week before the class period assigned for the discussion, with the following instructions: “Please go to the ACS website and find and download a copy of the paper. Print it out and as you read the paper, make notes on the paper and bring these to class with you. We will be using this paper to answer the following questions:” Alternatively, the paper could be downloaded by the instructor and either emailed or handed out to the students. In order to answer one of the questions, a table of thermodynamic values from the NIST website has been provided.

 

In order to reassure students who might be shy or hesitant about speaking up, students should be advised that they will not be graded on the correctness of the answer, but rather on their preparation and participation.

 

During the literature discussion, each student will be selected to answer a subset of the questions orally and/or on the board to start the discussion of that question. At the end of the literature discussion, the students will hand in the notes they have on each of the discussion questions, which they can edit during the discussion. The students be evaluated based on two criteria:

 

1.       Preparation: Did the students come to the discussion will thoughtful answers to the questions they were assigned?


2.       Participation: Did the students participate in the discussion of answers assigned to others? Did they communicate original ideas and questions clearly during the discussion?

1 Jul 2015

Advanced Inorganic Chemistry Course Videos

Submitted by Kathryn Haas, Saint Mary's College, Notre Dame, IN
Evaluation Methods: 

3 x 1 hour exams, ACS INorganic Chemistry Final Exam.

Description: 

At this website, you will find a link to the syllabus and all lecture videos for a "flipped" version of an Advanced Inorganic Chemistry Course taught at Saint Mary's College (Notre Dame, IN).  I used Shiver & Atkins for this course, and the format is based off of Dr. Franz's course at Duke.  If anyone is interested in the problem sets, I will be happy to share, although much of the material I used is from VIPEr.  

Learning Goals: 

Students will be able to apply fundimental principles of Group Theory, M.O. Theory, Acid/Base Theory, Crystal Field Theory, Kinetic & Thermodynamic trends, and 18e- rule  to understand spectroscopic (Absorption, Vibrational) and magnetic properties and to understand bonding and reactivity of metals.

 

Implementation Notes: 

This was the first iteration of a flipped model, I appologise for any mistakes & innacuracies, but if you spot issues, I'm happy to know about them.  The videos are rather long, and I will say that if I do this again, I will certainly design shorter videos!  Students really like it when the videos are 10-15 min or less.  But, perhaps these can help some beginning teachers prepare for class.  (And if that's you, good luck!)

Time Required: 
1 semester, 3 credit hour course
12 Nov 2014

Thinking about Mechanisms of Metal Ion Exchange

Submitted by Christian R. Goldsmith, Auburn University
Evaluation Methods: 

I consider the exercise to be a success when there is a high level of discussion. The groups that more animatedly discuss the material usually come up with a more informed answer.

Periodically, some groups will just sit there and wait for other groups to present their thoughts on the exercise. Sometimes, they can be prompted to be more proactive. Other times...

Evaluation Results: 

Typically, the students struggle to weight the two seemingly contradictory bits of information. They know that first-order rate laws are associated with dissociative mechanisms and that negative entropies of activation are associated with associative mechanisms. Many of the examples that they previously encountered had everything agree and didn't require them to evaluate the limitations of the provided data. They are rarely asked to choose.

Many students will realize that the entropy of activation is an imperfect indicator and determine that the rate-determing step involves the loss of the sodium. About one third to one half, however, will not. These students will tend not to settle on a mechanism.

This said, most students have really liked this exercise as it does give them an opportunity to think more critically about the issues discussed in class.

Description: 

Over the past several years, I've been doing this in-class exercise shortly after discussing mechanisms of ligand exchange. The exercise expands on the lecture material by having the students think about metal ions, rather than ligands, exchanging from a coordination complex. The students are encouraged to work in groups of 3-5 and actively discuss the material amongst themselves before we go over it as a class. I do not provide the students with the article ahead of time, so that they may come up with their own conclusions, as opposed to simply repeating those of the authors. I do encourage the class to read the article afterwards.

One item that I stress to my students is that coming up with a working mechanism is not usually a straightforward process. In certain cases, one needs to carefully weight contradicting bits of information, as the authors did in the source manuscript. Further, whichever mechanism one eventually settles on remains, at best, an educated guess.

In the current study, the rate law is inconsistent with an associative-type mechanism in which the iron reacts with the bimetallic complex before the loss of the sodium. This would seemingly be inconsistent with the negative entropy of activation. This parameter, however, will be influenced by solvation, and a more ordered outer-sphere in the transition state would explain this value and obscure a dissociative-type process. It may very well be that the sodium coordinates to water molecules before its dissociates from the ligand.

The exercise is meant for an upper-level class since it requires a solid understanding of kinetic parameters and kinetics. I have presented the exercise after introducing A, D, and I mechanisms for ligand exchange and discussing several case studies involving square planar and octahedral coordination compounds. I typically give the students about 10-15 min to work on this.

Learning Goals: 

The goal would be to get the students to think more critically about the data that one can acquire in a mechanistic study. In the course of the exercise they will need to evaluate how reliable each datum is and put forward a mechanism that is consistent with the entire set of data.

Corequisites: 
Course Level: 
Equipment needs: 

None. This can be done on the board, although a projector would allow the crystal structure of the bimetallic compound to be presented more quickly and clearly.

Subdiscipline: 
Time Required: 
10-15 min
23 Sep 2014

Five Slides about Spectroelectrochemistry (SEC)

Submitted by Kyle Grice, DePaul University
Description: 

This "Five slides about" is meant to introduce faculty and/or students to Spectroelectrochemistry (SEC), a technique that is used in inorganic chemistry research and other areas. SEC is a powerful tool to examine species that are normally hard to synthesize and isolate due to instability and high reactivity. Papers with examples of SEC techniques are provided on the last slide. 

 

Corequisites: 
Course Level: 
Learning Goals: 

Students should be able to describe spectroelectrochemistry

Students should be able to conceptually explain how a spectroelectrochemical cell works 

Students should be able to explain the benefits of spectroelectrochemistry as compared to standard synthesis and spectroscopy approches

Implementation Notes: 

Ideally, the students would take this introduction and then go and examine specific instances of SEC in the literature. Alternatively, this can be used to help explain research papers that are being discussed that use SEC techniques. 

Students should already have an understanding of the basics of electrochemistry and spectroscopy prior to learning SEC, so this would be best suited for an upper division, special topics course in Inorganic Chemistry or Spectroscopy. There are some nice LO's on these techniques already on Ionic Viper (see related activities). 

There are some good images of the specifics of SEC cell designs on company websites or journal articles (the Organometallics article shown in the web resources is one such article). 

IR-SEC is included in the paper that is the focus of the "Dissection Catalysts for Artificial Photosynthesis" LO. 

Time Required: 
15 min
Evaluation
Evaluation Methods: 

This LO was made as a followup to the 2014 Ionic Viper workshop and has not been implemented yet. However, I plan on implementing it in a "Special Topics in Inorganic Chemisry" course in the future. 

Evaluation Results: 

None yet, will be provided upon implementation. 

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