Second year

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.

31 Jul 2017

Inorganic Nomenclature: Naming Coordination Compounds

Submitted by Gary L. Guillet, Georgia Southern University Armstrong Campus
Evaluation Methods: 

For my course I grade this assignment as a problem set.  Upon collecting the assignment I do not exhaustively grade them.  I check them over for completness.  I tell the students when I hand it out that it is designed for them to learn and then test their own comprehension and if they are stuck they should bring issues to office hours. 

On the following exam I put two or three inorganic complex names and have the students draw the structures.  The test questions always incorporate isomerism in addition to combinations of common ligands and transition metals.

Evaluation Results: 

After completion of this assignment most students are able to draw straigthforward structures including some isomers on an exam.  They can identify common ligands from their names like water, ammonia, carbon monoxide.  They also understand the common conventions in naming including handling cis and trans isomers as well as fac and mer isomers.

In the most recent sample of ACS examinations (IN16D) 87% of my students answerd correctly on the question most directly related to this assignment, selecting the correct name of a given complex using a picture of the complex.  I do not have any comparative data from another teaching approach.

Description: 

I do not like to take a large amount of time in class to cover nomenclature of any kind though I want students to know the names of common ligands and the basic ideas of how coordination complexes are named.  Since it is a systematic topic I assign this guided inquiry worksheet.   The students complete it outside of class and can work at whatever pace they want.  If they are more familiar with the topics the can quickly complete it but if they are rusty or have not seen some of the material it gives them an easy entry point to ask questions to fill in any gaps in their knowledge.  This assignment covers determing charge on a metal in a complex with simple ligands, how to identify and name common isomers, and it is structured in a guided inquiry form. 

Learning Goals: 

Students will be able to identify and correctly name common ligands in a chemical structure or chemical name.

Students will be able to identify the charge on a metal or a ligand in a chemical structure.

Students will be able to identify common isomeric differences in a chemical structure or a chemical formula (cis, trans, fac, mer). 

Students will be able to use a chemical name to draw a chemical structure.

Equipment needs: 

None

Topics Covered: 
Corequisites: 
Prerequisites: 
Implementation Notes: 

I use this assignment to replace a lengthy lecture on the topic of nomenclature when covering coordination chemistry.  I have students complete this assignment outside of class.  I encourage them to work in pairs so students can jointly interpret the instructions and determine the patterns in naming complexes.  The assignment is constructed in a very straightforward manner and covers the basics of inorganic nomenclature.

Upon completion of the assignment I take about 15-20 minutes in class to quickly cover the main ideas of the assignment.  I field any questions that arose during the assignment and I do a few comprehension check type questions on the board. 

Time Required: 
1-2 hours
3 Jun 2017
Evaluation Methods: 

Evaluation methods could include grading as an in-class worksheet, trading with a partner for peer grading or turned in as an out-of-class graded homework assignment.

Evaluation Results: 

Currently, this activity has not been tested in a classroom.  Please post how your students did!

Description: 

This in-class activity is designed to assist students with the visualization of solid-state close-packed structures, using metal-sulfide nanocrystalline materials as a an example system.  Students will be asked to visualize and describe both hexagonal closest packed (hcp) and cubic closest packed (ccp) structure types, and isolate the tetrahedral and octahedral holes within each structure type.  Lasty, students will be asked to compare and contrast four metal-sulfide unit cells discussed in the paper below.

 

Powell, A.E., Hodges J.M., Schaak, R.E. Preserving Both Anion and Cation Sublattice Features during a Nanocrystal Cation-Exchange Reaction: Synthesis of a Metastable Wurtzite-Type CoS and MnSJ. Am. Chem. Soc. 2016, 138, 471-474.

http://pubs.acs.org/doi/abs/10.1021/jacs.5b10624

Learning Goals: 

In answering these questions, a student will…

  •  ...develop stronger visualaztion skills for extended, solid state materials;
  •  ...compare the packing sequence of close packed structures;
  •  ...locate tetrahedral and octahedral holes in close packed systems;
  •  ...count the number of tetrahedral / octahedral holes relative to the lattice ions; and
  •  …determine the number of atoms in a unit cell.
Equipment needs: 

The use of software - such as the demo version of CrystalMaker (http://www.crystalmaker.co.uk) or StudioViewer (Esko - app stores) - will be really helpful. StudioViewer can be run on cell phones, tablets, or MacOS devises. CrystalMaker is available for both Mac and PC. 

Instructions on using Studio Viewer to visualize structures on mobile devices are available in the learning object, Visualizing solid state structures using CrystalMaker generated COLLADA files.

 

Corequisites: 
Prerequisites: 
Implementation Notes: 

This learning object was developed at the 2017 MARM IONiC workshop on VIPEr and Literature Discussions. It has not yet been implemented.

This could be assigned for homework, but would likely work better in class with guidance. 

Time Required: 
This will probably take 50 minutes depending on how much work with models you do.
3 Jun 2017

Literature Discussion of "A stable compound of helium and sodium at high pressure"

Submitted by Katherine Nicole Crowder, University of Mary Washington
Evaluation Methods: 

Students could be evaluated based on their participation in the in-class discussion or on their submitted written answers to assigned questions.

Evaluation Results: 

This LO has not been used in a class at this point. Evaluation results will be uploaded as it is used (by Spring 2018 at the latest).

Description: 

This paper describes the synthesis of a stable compound of sodium and helium at very high pressures. The paper uses computational methods to predict likely compounds with helium, then describe a synthetic protocol to make the thermodynamically favored Na2He compound. The compound has a fluorite structure and is an electride with the delocalization of 2e- into the structure.

This paper would be appropriate after discussion of solid state structures and band theory.

The questions are divided into categories and have a wide range of levels.

Dong, X.; Oganov, A. R.; Goncharov, A. F.; Stavrou, E.; Lobanov, S.; Saleh, G.; Qian, G.-R.; Zhu, Q.; Gatti, C.; Deringer, V. L.; et al. A stable compound of helium and sodium at high pressure. Nature Chemistry 2017, 9 (5), 440–445 DOI: 10.1038/nchem.2716.

Corequisites: 
Learning Goals: 

After reading and discussing this paper, students will be able to

  • Describe the solid state structure of a novel compound using their knowledge of unit cells and ionic crystals
  • Apply band theory to a specific material
  • Describe how XRD is used to determine solid state structure
  • Describe the bonding in an electride structure
  • Apply periodic trends to compare/explain reactivity
Implementation Notes: 

The questions are divided into categories (comprehensive questions, atomic and molecular properties, solid state structure, electronic structure and other topics) that may or may not be appropriate for your class. To cover all of the questions, you will probably need at least two class periods. Adapt the assignment as you see fit.

CrystalMaker software can be used to visualize the compound. ICE model kits can also be used to build the compound using the template for a Heusler alloy.

Time Required: 
2 class periods
3 Jun 2017

An ion exchange method to produce metastable wurtzite metal sulfide nanocrystals

Submitted by Janet Schrenk, University of Massachusetts Lowell
Evaluation Methods: 

Evaluation methods are at the discretion of the instructor. For example, you may ask students to provide written answers to the questions, evaluate whether they participated in class discussion, or ask students to present their answers to specific questions to the class.

Description: 

In this literature discussion, students use a paper from the literature to explore the synthesis, structure, characterization (powder XRD, EDS and TEM) and energetics associated with the production of a metastable wurtzite CoS phase. Students also are asked define key terms and acronyms used in the paper; identify the goal of the experiments and determine if the authors met their goal. They examine the fundamental concepts around the key crystal structures available.  

 

Preserving Both Anion and Cation Sublattice Features during a Nanocrystal Cation-Exchange Reaction: Synthesis of a Metastable Wurtzite-Type CoS and MnS

Powell, A.E., Hodges J.M., Schaak, R.E. J. Am. Chem. Soc. 2016, 138, 471-474.

http://pubs.acs.org/doi/abs/10.1021/jacs.5b10624

 

There is an in class activitiy specifically written for this paper. 

Corequisites: 
Prerequisites: 
Learning Goals: 

In answering these questions, a student will be able to…

  • define important scientific terms and acronyms associated with the paper;

  • describe the rocksalt, NiAs, wurtzite, and zinc blende in terms of anion packing and cation coordination;

  • differentiate between the structure types described in the paper;

  • explain the difference between thermodynamically stable and metastable phases and relate it to a free energy diagram; and

  • describe the structural and composition information obtained from EDS, powder XRD, and TEM experiments.

Implementation Notes: 

This learning object was created at the 2017 IONiC Workshop on VIPEr and Literature Discussion. It has not yet been used in class.

Time Required: 
50 minutes
3 Jun 2017
Evaluation Methods: 

This LO was craeted at the pre-MARM 2017 ViPER workshop and has not been used in the classroom.  The authors will update the evaluation methods after it is used.

Description: 

This module offers students in an introductory chemistry or foundational inorganic course exposure to recent literature work. Students will apply their knowledge of VSEPR, acid-base theory, and thermodynamics to understand the effects of addition of ligands on the stabilities of resulting SiO2-containing complexes. Students will reference results of DFT calculations and gain a basic understanding of how DFT can be used to calculate stabilities of molecules.

 
Prerequisites: 
Corequisites: 
Learning Goals: 

Students should be able to:

  1. Apply VSEPR to determine donor and acceptor orbitals of the ligands

  2. Identify lewis acids and lewis bases

  3. Elucidate energy relationships

  4. Explain how computational chemistry is beneficial to experimentalists

  5. Characterize bond strengths based on ligand donors

Course Level: 
Implementation Notes: 

Students should have access to the paper and have read the first and second paragraphs of the paper. Students should also refer to scheme 2 and table 2.

 

This module could be either used as a homework assignment or in-class activity. This was created during the IONiC VIPEr workshop 2017 and has not yet been implemented.

 
Time Required: 
50 min
3 Jun 2017

Quantum Dot Growth Mechanisms

Submitted by Chi Nguyen, United States Military Academy
Evaluation Methods: 

The question document attempted by students in preparation for the literature discussion will be due prior to the in-class discussion. In particular, students' performance on the particle-in-a-box question will be evaluated to assess retention from the previously covered course material. The next exam following the discussion will contain specific question(s) (data/figure analysis) addressing these topics. Students' performance difference between the two will be evaluated. The extent to which students improve their post-discussion understanding of the concepts will direct future implementation.

Evaluation Results: 

To be determined. This is a newly proposed literature discussion.

Description: 

This literature article covers a range of topics introduced in a sophomore level course (confinement/particle-in-a-box, spectroscopy, kinetics, mechanism) and would serve as a an end-of-course integrated activity, or as a review activity in an upper level course. The authors of the article employ UV-vis absorption spectroscopy of CdSe quantum dots as a tool to probe the growth mechanism of the nanoparticles, contrasting two pathways.

 

Reference:  DOI 10.1021/ja3079576 J. Am. Chem. Soc. 2012, 134, 17298-17305

 
Corequisites: 
Prerequisites: 
Learning Goals: 

Apply the particle in a box model to interpret absorbance spectra with respect to nanoparticle size.

 

Analyze the step-growth and living chain-growth mechanisms proposed in this paper.

 

Evaluate the kinetics as it applies to the step-addition.

 

Recognize and apply multiple scientific concepts in an integrative manner.
Implementation Notes: 

Sophomore level implementation:  Recommend focusing on select portions (e.g. Figures 1b, 2, 5 with corresponding text) of the paper rather than having students read the entire document.  The learning objects focus on select topics, such as particle-in-a-box, reaction mechanism, and kinetics in conjunction with absorbance spectroscopy.  This would be a good literature discussion resource for an end-of-course integrative experience that encompasses multiple topics from general chemistry and inorganic chemistry.  

 

Advance level implementation:  For an upper division course, incorporate the paper in its entirety early in the course as an assessment on students’ ability to integrate multiple concepts that they should have learned in general chemistry, organic chemistry, and physical chemistry.  To enhance the experience, accompanying the literature discussion on this paper with a laboratory experience by repeating the experimental and characterization procedures presented in the paper, and having students' compare their results with published results.  This also serves to enhance students’ scientific literacy by critically assessing the quality of the paper.

 

Excerpts of the paper and questions can be used on a graded event, or as lesson preparation for in class discussion.

 
Time Required: 
In-class discussion takes approximately 50 minutes with students having already read the paper and submitted their responses to the questions.
3 Jun 2017
Evaluation Methods: 

This was created during the IONiC VIPEr workshop 2017 and has not yet been implemented.

 
Description: 

This module offers students an introductory chemistry or foundational inorganic course exposure to recent literature work. Students will apply their knowledge of VSEPR and basic bonding to predict geometries of complex SiO2-containing structures. Students will gain a basic understanding of how crystallography is used to determine molecular structures and compare experimental crystallographic data to their predictions.

Prerequisites: 
Course Level: 
Corequisites: 
Learning Goals: 

Students will be able to:

  1. Describe the bonding in SiO2 and related compounds
  2. Apply bonding models to compare and contrast bond types
  3. Apply VSEPR to predict bond angles
  4. Utilize crystallographic data to evaluate structures
Implementation Notes: 

Students should have access to the paper and read the first and fourth paragraphs on the first page and the third paragraph on the second page. Students should also reference scheme 1 and figure 1.

 

This module could be either used as a homework assignment or in-class activity.

 
3 Jun 2017

Fivefold Bonding in a Cr(I) Dimer Updated and Expanded

Submitted by Thomas Brown, SUNY Oswego
Evaluation Methods: 

Students are asked to answer the questions before coming to class and collected. After discussion students can revise their answers.   

Evaluation Results: 

This is a newly revised learning object so no assessment has been collected yet.  

Description: 

This paper describes the synthesis and characterization of a Cr(I) dimer with a very short Cr-Cr distance. Computational studies support fivefold bonding between the chromium atoms. This paper could be used to introduce metal-metal multiple bonds and discuss the molecular orbital interactions of homonuclear diatomics including d-orbitals. More generally, it is a nice example to stimulate the discussion of what constitutes a bond and the various interpretations of bond order. This version of this learning object is a modified and expanded version of Maggie Geselbracht's original LO. It was prepared colleaboratively at the 2017 VIPEr Literature Discussion workshop.

Corequisites: 
Learning Goals: 
Students should be able to:
  • Identify shapes and orientation of d orbitals

  • Create Lewis structures describing ligand binding type from crystal structures.

  • Apply symmetry concepts to assign orbital symmetries and create molecular orbital diagrams

  • Develop and draw the MO diagram of d-orbital interactions and use it to interpret the bonding involved in metal-metal multiple bonds.

  • Evaluate the relationship between bond order and experimental metal-metal bond distance

  • Evaluate effects of ligand design on molecular stability

  • Apply character tables for associated molecular point groups      

  • Rationalize MO interactions of ligands with metal centers in the presence of a metal-metal multiple bond.

 

Implementation Notes: 

Students are asked to read the paper and answer the discussion questions before coming to class. This could be used in an inorganic course after you have talked about MO theory of diatomics but fairly early in our discussion of transition metal chemistry. There is a Perspectives article in Science that goes along with this paper that gives the MOs more explicitly.   

Time Required: 
50 min +
3 Jun 2017
Evaluation Methods: 

This learning object was created at the pre-MARM workshop in 2017 and as such has not been used in a classroom setting. The authors will update the learning object once they have used it in their classes.

Description: 

This module offers students in an introductory chemistry or foundational inorganic course exposure to recent literature. Students will apply their knowledge of Lewis dot structure theory and basic thermodynamics to compare and contrast bonding in SiO2 and CO2.

Corequisites: 
Course Level: 
Prerequisites: 
Learning Goals: 

Students should be able to:

  1. Describe the bonding in SiO2 and related compounds (CO2)

  2. Use Lewis dot structure theory to predict bond orders

  3. Apply bonding models to compare and contrast bond types and bond energies (sigma, pi)

  4. Characterize bond strengths based on ligand donors

Implementation Notes: 

Students should read the first paragraph of the paper prior to completing this learning object. They can be encouraged to read more of the paper, but the opening paragraph is the focus of this learning object.

Time Required: 
50 min

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