Organometallic Chemistry

26 Mar 2019

Redox-switch polymerization catalysis

Submitted by Chip Nataro, Lafayette College
Evaluation Methods: 

I am really unsure at this point. I may use the 1FLO version of this as a series of exam quesitons, or I may have the students work on this literature discussion in class. Either way, I am excited to see what they will do with it.

Description: 

This is the full literature discussion based on a communicaiton (J. Am. Chem. Soc. 2011133, 9278). This paper describes a redox-switch yttrium catalyst that is an active catalyst for the polymerization of L-lactide in the reduced form and inactive in the oxidized form. The catalyst contains a ferrocene-based ligand that serves as the redox active site in the catalyst. This full literature discussion is an extension of the one figure literature discussion that is listed below. In addition to presenting all of the same questions as that learning object, this includes interpretation of the XANES spectra presented in the paper. It also asks the students to identify the monomer and polymer in the reaction of interest. A possible extension of this learning object would be to have students examine and take measurements from the crystal structure presented in the paper in order to support the apparently low electron count on the yttrium catalyst. The Covalent Bond Classification system for counting electrons is used in this learning object.

Corequisites: 
Course Level: 
Learning Goals: 

A student should be able to apply their knowledge to 

  1. describe and interpret a plot of conversion vs. time
  2. count electrons and determine valence states in organometallic compounds
  3. determine if an organometallic compound is an oxidizing or reducing agent
  4. decipher a first-order kinetic plot
  5. interpret XANES spectra to determine the valence of iron in the catalyst
Subdiscipline: 
22 Mar 2019

1FLO: Redox-switch polymerization catalysis

Submitted by Chip Nataro, Lafayette College
Evaluation Methods: 

I am really unsure at this point. I could certainly see this being used as a series of exam questions or have students take a few minutes to think about the questions individually and then have them share with a small group and present their thoughts in class. This is actively interpreting a figure from the literature with almost no context. As such, it is certainly going to be indicative of their understanding of other ideas and concepts.

Description: 

This is what I hope will be a new classification of learning object called a one figure learning object (1FLO). The purpose is to take a single figure from a paper and present students with a series of questions related to interpreting the figure. This literature discussion is based on a paper (J. Am. Chem. Soc. 2011, 133, 9278) from Paula Diaconescu's lab in which a yttrium polymerization catalyst with a ferrocene-based ligand can effectively be rendered active or inactive depeneding on the valence state of the ligand. The figure chosen from the paper shows the conversion of the monomer (L-lactide) to polymer over the course of time. During the reaction, the valence state of the ligand is changed and the rate of polymerization is significantly impacted. While the purpose of this LO was to limit consideration to a single figure, there is so much to mine from this communication that a companion literature discussion was developed to go into more of the details that were presented. Certainly this 1FLO can stand alone or be used in conjunction with the companion literature discussion. The Covalent Bond Classification system for counting electrons is used in this learning object.

Corequisites: 
Subdiscipline: 
Learning Goals: 

A student should be able to apply their knowledge to

  1. describe and interpret a plot of conversion vs. time
  2. count electrons and determine valence states in organometallic compounds
  3. determine if an organometallic compound is an oxidizing or reducing agent
  4. decipher a first-order kinetic plot
Course Level: 
Implementation Notes: 

I have yet to use this but I anticipate doing so in the fall. I hope it works as well as I think it can. It is such a simple plot and yet it is so rich in chemistry. I have a feeling I am going to have a very hard time containing myself to just this LO and not using the companion full Literature Discussion.

Time Required: 
Unknown but I think it could be as short as 15 minutes
31 Jan 2019
Evaluation Methods: 

Students were evaluated informally as I walked around to help the groups as well as during presentations.

Evaluation Results: 

A large majority of the students had no problem making assignments for the simple and intermediate cases.  This outcome is largely a testament to the ease of use of the CBC method.  In fact, students who had no background in inorganic or organometallic chemistry tended to perform a little better because they were less likely to bring in preconceptions about "oxidation state".

Students struggled a bit with the Z-type Ga ligand, which is great because it helped them move forward in understanding the periodic relationship to Al and B.  Students also struggled a bit with the cyclic (alkyl)aminocarbene ligands in the cobalt dimer, since they had not seen those before.

 

Description: 

This in-class group activity extends my original post by providing more examples of varying difficulty for students to assign MLXZ classifications and electron counts to organometallic complexes.  The answers to these are unambiguous within the CBC system, but they provide excellent starting points for conversation with students about bonding formalisms with organometallics.

Learning Goals: 

* Students should be able to use the covalent bond classification method to assign MLXZ classifications to a variety of organometallic complexes.

* Students should be able to defend their assignments using both organic and inorganic views of structure and bonding.

* Students will understand the ambiguities associated with assigning bond orders, valencies, oxidation states, etc., with the hope that their understanding of covalently bonded organometallic systems will become more nuanced.

 

Course Level: 
Corequisites: 
Implementation Notes: 

I split students into groups of 3, as noted in the handout.  Since this was a small class, I used 10 problems (all 7 from this handout and 3 from the earlier activity) and each student presented one answer.  Students took about 25 minutes to work through the problems, and then I had the students present and encouraged questions and challenges to their assignments.  The students brought several interesting insights that deepened their understanding of bonding and the connection between Organic Chemistry (which they have all taken) and Inorganic/Organometallic Chemistry (which most of them have not seen).

 

Time Required: 
45 minutes
31 Jan 2019
Description: 

This set of slides was made for my Organometallics class based on questions about bridging hydrides and specifically the chromium molecule. I decided to make these slides to answer the questions, and do a DFT calc to show the MO's involved in bonding of the hydride. 

 

Corequisites: 
Learning Goals: 

A student will be able to explain bridging hydride bonding

A student will be able to perform electron counting on a chromium comples with a bridging hydride

A student will be able to interepret calculated DFT molecular orbitals. 

Time Required: 
15 min
Evaluation
Evaluation Methods: 

This was provided as supplementary material outside of lecture. 

28 Jan 2019
Evaluation Methods: 

Concepts covered during literature discussions will be included among exam materials.

Evaluation Results: 

N/A

Description: 

This Guided Literature Discussion was assigned as a course project, and is the result of work originated by students Joie Games and Benjamin Melzer.  It is based on the article “Next-Generation Water-Soluble Homogeneous Catalysts for Conversion of Glycerol to Lactic Acid” by Matthew Finn, J. August Ridenour, Jacob Heltzel, Christopher Cahill, and Adelina Voutchkova-Kostal in Organometallics 2018 37 (9), 1400-1409. It includes a Reading Guide that will direct students to specific sections of the paper that were emphasized in the discussion.  This article reports a systematic study of a series of homogeneous catalysts for the conversion of glycerol to lactic acid.

Course Level: 
Corequisites: 
Learning Goals: 

After reading and discussing this article, a student should be able to…

-       Apply the CBC electron-counting method to homogeneous catalysts.

-       Understand the effect of metal and/or metal oxidation state on catalyst activity.

-       Understand the effect of ligand and/or ligand charge on catalyst activity.

-       Understand the differences between microwave and conventional heating.

Implementation Notes: 

I am planning on assigning this LO as a graded in-class group discussion. Students will be given a copy of the article, reading guide, and discussion questions one week in advance. On the day of the discussion, students will be assigned in groups of 2-3. They will then have one lecture period to answer the questions in writing as a group. A portion of their grade (20%) is dedicated to literature discussions (4-6 over the course of the semester). The grading rubric involves 3 possible ratings for each question/answer: “excellent”, “acceptable”, or “needs work”. [This article is among the free-access ACS Editors’ Choice.]

Time Required: 
1 lecture period, with materials given one week in advance
28 Jan 2019
Evaluation Methods: 

A portion of their grade (20%) is dedicated to literature discussions (4-6 over the course of the semester). The grading rubric involves 3 possible ratings for each question/answer: “excellent”, “acceptable”, or “needs work”.

Concepts covered during literature discussions will be included among exam materials.

Evaluation Results: 

N/A

Description: 

This Guided Literature Discussion was assigned as a course project, and is the result of work originated by students Christopher Lasterand Patrick Wilson.  It is based on the article “Deca-Arylsamarocene: An Unusually Inert Sm(II) Sandwich Complex” by Niels J. C. van Velzen and Sjoerd Harder in Organometallics 201837, 2263−2271. It includes a Reading Guide that will direct students to specific sections of the paper that were emphasized in the discussion.  This article presents a study of the reactivity of bulky CpAr-Et/iPrSm complexes that is contrasted to the more well-known Cp*2Sm.

Course Level: 
Corequisites: 
Learning Goals: 

After reading and discussing this article, a student should be able to…

-      Be more familiar with the chemistry of sandwich samarocene complexes.

-      Understand how bulky ligands affect structure and reactivity in a sandwich complex.

-      Apply the CBC method to identify ligand functions and metal valence number/ligand bond number.

-       Understand how XRD bond distances can help determine a ligand charge.

Implementation Notes: 

I am planning on assigning this LO as a graded in-class group discussion. Students will be given a copy of the article, reading guide, and discussion questions one week in advance. On the day of the discussion, students will be assigned in groups of 2-3. They will then have one lecture period to answer the questions in writing as a group.  [This article is among the free-access ACS Editors’ Choice.]

Time Required: 
1 lecture period, with materials given one week in advance
16 Jan 2019
Evaluation Methods: 

Concepts covered during literature discussions will be included among exam materials.

Evaluation Results: 

N/A

Description: 

This Guided Literature Discussion was assigned as a course project, and is the result of work originated by students Jana Forster and Kristofer Reiser.  It is based on the article “Mechanism of the Platinum(II)-Catalyzed Hydroamination of 4-Pentenylamines” by Christopher F. Bender, Timothy J. Brown, and Ross A. Widenhoefer in Organometallics 2016 35 (2), 113-125. It includes a Reading Guide that will direct students to specific sections of the paper that were emphasized in the discussion.  This article presents a mechanistic study of hydroamination reactions catalyzed by a late transition metal complex.

Course Level: 
Corequisites: 
Learning Goals: 

After reading and discussing this article, a student should be able to…

-  Apply the CBC electron-counting method.

-  Understand how 31P {1H} NMR can help differentiate intermediates.

-  Use information provided by Eyring plots.

-  Understand how a catalyst resting state and turnover-limiting step can be identified.

-  Understand the role of kinetics in mechanistic investigations.

-   Appreciate how proposed reaction mechanisms can be evaluated.

 

Implementation Notes: 

I am planning on assigning this LO as a graded in-class group discussion. Students will be given a copy of the article, reading guide, and discussion questions one week in advance. On the day of the discussion, students will be assigned in groups of 2-3. They will then have one lecture period to answer the questions in writing as a group. A portion of their grade (20%) is dedicated to literature discussions (4-6 over the course of the semester). The grading rubric involves 3 possible ratings for each question/answer: “excellent”, “acceptable”, or “needs work”. [This article is among the free-access ACS Editors’ Choice.]

Time Required: 
1 lecture period, with discussion materials given one week in advance
3 Jan 2019

Venn Diagram activity- What is inorganic Chemistry?

Submitted by Sheila Smith, University of Michigan- Dearborn
Evaluation Methods: 

I did not assess this piece, except by participation in the discussion

Evaluation Results: 

I asked my students to write an open ended essay to answer the question (asked in that first day exercise): What is Inorganic Chemistry.

Interestingly, 2 of my 15 students drew a version of this Venn Diagram to accompany their essays.

Description: 

This Learning Object came to being sort of (In-)organically on the first day of my sophomore level intro to inorganic course. As I always do, I started the course with the IC Top 10 First Day Activity. (https://www.ionicviper.org/classactivity/ic-top-10-first-day-activity).  One of the pieces of that In class activity asks students- novices at Inorganic Chemistry- to sort the articles from the Most Read Articles from Inorganic Chemistry into bins of the various subdisciplines of Inorganic Chemistry.  As the discussion unfolded, I just sort of started spontaneously drawing a Venn Diagram on the board.  

I think Venn diagrams are an excellent logic tool, one that is too little applied these days for anything other than internet memes.  This is a nice little add-on activity to the first day.
 

Your Venn diagram will likely look different from mine.  You're right.

 

Learning Goals: 

The successful student should be able to:

  • identify the various sub-disciplines of inorganic chemistry.  
  • apply the rules of logic diagrams to construct overlapping fields of an Venn diagram.

 

Prerequisites: 
Corequisites: 
Equipment needs: 

colored chalk may be handy but not required.

Implementation Notes: 

I used this activity in conjuction with a first day activity LO (also published on VIPEr).

I shared a clean copy (this one) with the students after the class where we discussed this.

 

Time Required: 
10-15 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.
12 Jan 2018

Geometry Indices

Submitted by Anthony L. Fernandez, Merrimack College
Description: 

In the primary literature, goemetry indices are being used quite often to describe four- and five-coordinate structures adopted by transition metal complexes. This slide deck, which is longer than the intended 5 slides, describes the three common geometry indices (tau4, tau4', and tau5) and provides example calculations for structures that are freely available in the Teaching Subset of the Cambridge Structural Database. (Students can access these structures in Mercury, which is freely available from the CCDC, or via a web request form for which the link is provided below.)

Corequisites: 
Prerequisites: 
Learning Goals: 

After viewing this presentation, students should be able to:

  • recall the common geometries adopted by transition metal centers in four- and five-coordinate structures,
  • describe the limiting geometries for each CN,
  • recall the formulas for the three geometry indices (tau4, tau4', and tau5),
  • calculate the value of the appropriate geometry index for a given structure, and
  • identify the geometry exhibited by a TM center.
Implementation Notes: 

I have found that this presentation can be used effectively in one of several ways:

  • the presentation is given in class and then students complete an exercise in which they calculate the geometry indices for a number of transition metal complexes before the leave class,
  • the presentation is given in class and then students complete an exercise in which they calculate the geometry indices for a number of transition metal complexes outside of class (as homework), or
  • the presentation is provided to them as a PDF file as part of the pre-class assignment and then students complete an exercise in which they calculate the geometry indices for a number of transition metal complexes when they are in class.
Time Required: 
20-30 minutes
Evaluation
Evaluation Methods: 

I use these slides to introduce the concept of geometry indices in class. Since this is a presentation, I do no formal evaluation of the impact of these slides on student learning. 

I do ask students to complete several exercises in which they calculate the geometry indices for a number of transition metal complexes. 

Evaluation Results: 

Over several years, I have observed that students very rarely have trouble completing the assigned exercises correctly after viewing this presentation.

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