Coordination Chemistry

6 Jun 2019
Evaluation Methods: 

The classroom discussion (participation, answers, etc) may be assessed by the instructor, or alternatively, these questions could be given to students to turn in.

Evaluation Results: 

None yet available.  Please leave yours in the comments!

Description: 

This literature discussion aims to have students in an advanced inorganic chemistry course interpret reaction schemes and electronic spectra, relate chemical formulae to molecular structure, and gain an understanding of how inorganic synthesis is planned and executed.  Students should gain an understanding of how counterions and crown ethers affect structure. Question 7 may be expanded to ask students to why pi-donor ability affects ligand field splitting, or as an introfuction to this topic.

An associated 1FLO based on this paper is linked in the related content.

 

Corequisites: 
Course Level: 
Learning Goals: 
Students will be able to:
  • Interpret reaction schemes and write balanced equations.
  • Rationalize the position of a ligand in the spectrochemical series based upon its π-donor/acceptor properties
  • Relate the electronic structure of tetrahedral d8 complexes to their magnetic properties
  • Analyze the impact of countercations on the geometry and electronic properties of the complexes.
Implementation Notes: 

This LO is intended for an advanced inorganic chemistry course.  Students should read the communication before class with questions above as guidance.  A classroom discussion should insue, in which students gain an insight into inorganic synthesis, and recognize how minor differences between compounds, such as counterions, have significant effects on electronic structure.

 

Time Required: 
50 minutes
6 Jun 2019

1FLO: Relating Electronic Spectra and Ligand Field Strength of [NiX4]2- Anions

Submitted by Wesley S. Farrell, United States Naval Academy
Evaluation Methods: 

Evaluate students' comprehension based on verbal in-class answers and ensuing discussion.

Evaluation Results: 

None yet available.

Description: 

This 1FLO asks students to interpret an electronic spectrum of 5 NiX42- anions.  Students will determine the relative ligand field strength, (re)familiarize themselves with terms such as "redshift" and "blueshift", and consider possible metal complex geometries.

Learning Goals: 
  1. Students (re)familiarize themselves with relationship between wavelength (λ) and wavenumber (cm-1).

  2. Students recall 4-coordinate geometries.

  3. Students define the terms “redshift” and “blueshift.”

  4. Students analyze data to construct a partial spectrochemical series.

Corequisites: 
Course Level: 
Equipment needs: 

None

Implementation Notes: 

This activity could be used as either a guided introduction to the spectrochemical series, or as an in-class activity to review after introduction.  If used as an introduction, question 4 may need modification.

Time Required: 
15 - 20 Minutes
5 Jun 2019

Zinc-Zinc Bonds (Expanded and Updated)

Submitted by Wesley S. Farrell, United States Naval Academy
Evaluation Methods: 

Performance and participation in the discussion will be assessed 

Evaluation Results: 

None collected yet. Evaluation data will be added in the future.

Description: 

This paper in Science reports the synthesis of decamethyldizincocene, a stable compound of Zn(I) with a zinc-zinc bond. In the original LO, the title compound and the starting material, bis(pentamethylcyclopentadienyl)zinc, offer a nice link to metallocene chemistry, electron counting, and different modes of binding of cyclopentadienyl rings as well as more advanced discussions of MO diagrams. More fundamental discussion could focus on the question of what constitutes the evidence for a chemical bond, in this case, the existence of a zinc-zinc bond. In this updated LO, these topics are still covered, however additional topics, such as point group idenitifaction, details regarding the reaction mechanism, electronic structure, and  searching the literature using SciFinder are covered.  Additionally, electron counting is divided into both the covalent and ionic models.

Corequisites: 
Course Level: 
Learning Goals: 
  1. Students should become more confident reading the primary literature

  2. Students should be able to apply existing knowledge to interpret research results.

  3. Students should be able to apply electron counting formalisms to organometallic compounds.

  4. Students should be able to use 1H NMR spectroscopy data to rationalize structure.

  5. Students can rationalize bond distances based on periodic trends in atomic radii

  6. Students use SciFinder to put this work into a larger context.

  7. Students identify redox reactions based on oxidation changes.

  8. Students identify molecular point groups based upon structures.

  9. Students should be able to connect d electron count to observed colors of compounds. 

Related activities: 
Implementation Notes: 

Students are asked to read the paper and the accompanying Perspectives article before class as well as answer the discussion questions. The questions serve as a useful starting point for class discussion. 

Time Required: 
50 minutes
28 May 2019

Quadruple Bond Acrobatics

Submitted by Lori Watson, Earlham College
Evaluation Methods: 

Students are typically asked one multiple chose or short answer question where they identify which d orbitals are involved in metal-metal quadruple bonding and/or idetify/draw the interaction.  They will also use these concepts in a more applied way in both problem set and exam in depth questions where they must explain particular structural or spectroscopic evidence using, for example, the ligand geometry forced by the eclipsed conformation of the dx2-y2 remaining d orbital.

Evaluation Results: 

Students generally perform very well on the basic identification/d-orbital interaction question that mostly tests recal of the facts.  There is a range of performance on more complex application problems, though students usually correctly identify the role of the quadruple bond orbitals and geometry as a factor.  Common challenges involve misidentification of axes, and an inability to think through how changes to variables like metal identity or oxidation state, or ligand sterics, may further contribute to observed bonding or structural data.

Description: 

Four pairs of students represent quadruple bonding in metal complexes by "forming bonds" with a variety of physical methods involving actions like facing each other while holding hands (sigma bond), touch hands and feet of their partner "above and below" the plane (two pi bonds), touching hands and feet while facing each other (delta bond).  This results in a "Twister"-like pile of students resembling the quadruple bonding interaction

 

Procedure:

1. Ask for 8 volunteers who are comfortable touching each other (holding hands, touching foot to foot)
2. Start with the shortest pair of students, and proceed through all four pairs having them do the following:

  • Sigma bond: have two students face each other at a comfortable distance, holding both hands.  The held hands represent electron density along the internuclear axis.  This is dz2
  • Pi bonds: have two pairs of students form the dxz and dyz bonds by having two students stand behind each of the first pair. They will represent pi electron density above and below the internuclear axis by touching hands together on either side (dxz) or a hand and foot above and below the axis respectively (dyz), where the y axis points toward the ceiling.  Unless your students can levitate, one foot must remain on the floor at all times--so the dxz orbital interaction is challenging, and one "lobe" (represented by the foot stick out toward the back) will not be properly represented.  
  • Delta bond: have the tallest students face each other, one behind each of the previous three students on their side.  Have them spread out their feet and hands at approximate right angles to each other, and then touch both hands palm to palm together above the z axis, and both feet together below th z axis.  To do this, the previous pairs of students will have to move even closer together, and the dxy orbitals will need to "bend" toward each other.  Students will observe that it's difficult to make good contact palm to palm.  Quadruple bonds are weaker!

3. Let the class dissolve into giggles, and then debrief.  How did each group of students have to move? Which orbital was "left out"? How would be expect incoming ligands to bind? Why? Could you have quintuple bonds? (Hint: yes) What would happen if the incoming ligands were too large to be eclipsed? (Hint: will tend to form staggered, triple bonded metal-metal complexes instead).

4. Give the class time to sketch out all four orbitals involved in a metal-metal quadruple bond in their notes.

Learning Goals: 

A student should be able to identify and draw the d orbitals involved in quadruple bonding, including their interactions.  They should be able to explain why quadruple bonds are shorter than corresponding triple bonds and where and which d orbital will be involved in bonding to ligands.

Prerequisites: 
Equipment needs: 

8 willing students who consent to physical contact with each other (holding hands, touching foot to foot).  It works best to begin with the shortest pair of students and proceed toward the tallest pair of students.

Corequisites: 
Implementation Notes: 

This works best when begining with the shortest pair of students and proceeding toward the tallest pair of students.

 

Please see attached pictures for a step-by-step guide to movement.

Time Required: 
5 minutes, plus 5 minutes debrief
12 Feb 2019

Advanced ChemDraw (2019 Community Challenge #2)

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

Students were evaluated during class for effort and participation, and the instructor gave immediate tips and feedback. After students submitted the assignment, it was graded for completion and effort.

 

Evaluation Results: 

Students were allowed to turn in the assignment 2 days later and 22/24 students completed the assignment. The most common errors were slight variances in bond angles and missing colors used in the literature figures. Overall, the quality of the submitted work was impressive, especially for second-year students.

Description: 

This in-class activity was designed for a Chemical Communications course with second-year students. It is the second part of a two-week segment in which students learn how to use ChemDraw (or similar drawing software to create digital drawings of molecules).

In this activity, students learn advanced techniques to visualize complex organometallic molecules and reaction schemes using ChemDraw. Students are presented with several images and reaction schemes taken directly from the organometallic literature and are tasked with recreating the images using ChemDraw. This gives students direct exposure to current literature, while learning useful skills in chemical visualization.

Learning Goals: 

Students will be able to:

1.    Convey 3-D structure of a molecule in a drawing.

2.    Recreate molecular drawings found in the literature.

3.    Create digital drawings of molecules using ChemDraw.

4.    Create digital drawings of reaction schemes & cycles.

Equipment needs: 

Computer for each student with ChemDraw installed.

Implementation Notes: 

This was implemented in a 24-student course in the week following an introduction to basic ChemDraw use. Students were shown the techniques in lecture format using the attached Powerpoint presentation. After the presentation, students had access to the slides and could refer to them while completing the activity. 

In-class most students were mostly able to complete the worksheet using the powerpoint slides as a guide. However, the instructor also walked around to give individual tips and instruction. 

The total time for the activity and lecture was 1 hour 50 min, but it could be shortened or assigned for homework.

In the section where students are asked to interpret molecular formulas, this is done ignoring ligand abbreviations, such as R groups or simplifications of chelating ligands. This could be left off, however it was a useful way to introduce students to drawing simplifications they may find in the literature. Most students just interpreted the formula based on what was drawn, and some students looked up the original papers to get a more accurate formula (although this takes much more time). 

 

Time Required: 
60-110 min
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

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