Symmetry

10 May 2018

3D Sym Op

Submitted by Caroline Saouma, University of Utah
Evaluation Methods: 

None

Description: 

This is a great app that helps students see the symmetry in molecules. It allows you to choose a molecule (by name, structure, or point group) and display a 3D rendition of it. You can then have it display the symmetry elements, and/or apply all the symmetry operations. 

It is available for both android and apple phones: (probably easier to just search for it)

apple: https://itunes.apple.com/us/app/3d-sym-op/id1067556681?mt=8

android: https://play.google.com/store/apps/details?id=com.nus.symmo&hl=en_US

Topics Covered: 
Prerequisites: 
Learning Goals: 

A student should be able to find symmetry elements in molecules. 

Corequisites: 
Implementation Notes: 

In class I project my phone screen so they can see it, and I encourage the students to work along with their phones. I prefer this to models, as it is hard to remember what things looked like before you did the transformation, and moreover, my students have a hard time finding the symmetry elements. 

 

I encourage the students to play with it anytime they have a few spare moments- waiting for the bus, in line for food, etc. 

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 Feb 2017

Six-coordinate Carbon In-class Activity

Submitted by Kyle Grice, DePaul University
Evaluation Methods: 

Dr. Grice will evaluate this LO later this year. 

Description: 

This is an in-class exercise developed based on a recent paper in Angewandte Chemie International Edition that reported a crystal structure of "six-coordinate" carbon. We normally think of carbon being four-coordinate at most, but this case has definitive evidence otherwise. However, we can use our inorganic chemistry knowledge to understand the structure and bonding of this molecule and rationalize its stability. Students do a pre-class exercise and then construct the MO of fhe molecule in class together. 

Learning Goals: 

After completion of this Learning Object, students will be able to:

-Assign point groups to organic molecules

-Analyze and discuss chemistry primary literature

-Identify the properties and charges of ligands

-Use Wade's rules to describe clusters

-Construct qualitative MO diagrams using symmetry as a guide

Corequisites: 
Course Level: 
Equipment needs: 

None

Prerequisites: 
Implementation Notes: 

Dr. Grice will be implementing this later this year. 

We have included an instructor guide file under Faculty files. 

Time Required: 
50 min
11 Jan 2017

Group VI metal carbonyl compounds with pincer ligands

Submitted by Chip Nataro, Lafayette College
Evaluation Methods: 

This was developed after the semester in which I teach this material. I look forward to using it next fall and I hope to post some evaluation data at that point.

Description: 

This literature discussion is based on a short paper describing a series of Group VI metal carbonyl compounds that have pincer ligands (Organometallics, 201635, 229). While the paper is relatively straightforward, there are many subtle points that can be brought out by asking the right questions which hopefully this LO does. Some of the questions the students should be able to answer directly from the paper. I feel it is important that they do this. However, these questions nicely set up further questions that require the students to go beyond what is covered in the paper. In addition to the synthesis, there are many questions related to the spectroscopic characterization of these compounds. And of course, it wouldn't be one of my LOs if students weren't being asked to count electrons and do group theory.

Corequisites: 
Prerequisites: 
Learning Goals: 

Upon completing this LO students should be able to

  1. Use the CBC method to count electrons in the tungsten compounds in this paper
  2. Describe the bonding interaction between a metal and a terminal carbonyl ligand
  3. Explain how NMR can be used to characterize these compounds including a discussion of 183W satellites
  4. Relate data from IR spectroscopy to the bonding interaction between a metal and a ligand and describe how the IR data can provide information about the electron donor ability of related ligands
  5. Recognize that some observed trends just do not have good explanations
 
Course Level: 
Implementation Notes: 

This might be a bit on the long side, you could certainly omit some of the questions or have the students work on it outside of class.

Time Required: 
50 minutes or so
4 Jan 2017
Description: 

This is a great new textbook by George Luther III from the University of Delaware.  The textbook represents the results of a course he has taught for graduate students in chemical oceanography, geochemistry and related disciplines.  It is clear that the point of the book is to provide students with the core material from inorganic chemistry that they will  need to explain inorganic processes in the environment.  However the material is presented in such a clear, logical fashion and builds so directly on fundamental principles of physical inorganic chemistry that the book is actually applicable to a much broader audience.  It provides a very welcome presentation of frontier orbital theory as a guide to predicting and explaining much inorganic chemical reactivity.  There are numerous very  helpful charts and tables and diagrams.  I found myself using the book for a table of effective nuclear charges when I was teaching general chemistry last semester.  The examples are much more interesting that the typical textbook examples and would be easy to embellish and structure a course around.  There is also a helpful companion website that provides powerpoint slides, student exercises and answers.  The book covers some topics not typically seen in inorganic textbooks like the acidity of solids but the presentation of this information makes sense in light of the coherent framework of the text.  We so often tell our students "structure dictates function".  This text really make good on that promise.  My only complaint is that I wish the title were something more generic so that I could use it for a second semester of introductory-esque material that we teach after students have taken a single semester of intro chem and two semesters of organic chemistry.  So much of what is covered in this textbook is precisely what a second semester sophomore chemistry major should know before proceeding on in the major.  But the title makes the book hard to sell to chemistry majors and that is regrettable. 

Prerequisites: 
Course Level: 
29 Dec 2016

The Monsanto acetic acid process

Submitted by Chip Nataro, Lafayette College
Evaluation Methods: 

This was developed after the semester in which I teach this material. I look forward to using it next fall and I hope to post some evaluation data at that point.

Description: 

This literature discussion is based on one of early papers detailing the mechanism for the Monsanto acetic acid process (J. Am. Chem. Soc., 1976, 98, 846). In this communicaiton the identification of key intermediates in this process is carried out using infrared spectroscopy. While the paper is an easy read, there are lots of subtle points that can be brought out by asking the right questions which hopefully this LO does. Although we have plenty of excellent LOs asking students to identify the individual steps in the catalytic mechanism, this LO takes a slightly different approach and marches students through the mechanism.

Course Level: 
Prerequisites: 
Corequisites: 
Subdiscipline: 
Learning Goals: 

Upon completing this LO students should be able to

  1. Use the CBC method to count electrons in the rhodium compounds in this paper
  2. Describe the bonding interaction between a metal and a terminal carbonyl ligand
  3. Identify the various reactions taking place in the Monsanto acetic acid process
  4. Relate data from IR spectroscopy to the bonding interaction between a metal and a ligand and to the identification of intermediates in this process
Time Required: 
50 minutes or so
28 Dec 2016

Virtual Issue of Organometallics

Submitted by Chip Nataro, Lafayette College

You can find the virtual issue with our editorial and all of the papers here.

Subdiscipline: 
Prerequisites: 
Corequisites: 
Course Level: 
11 Nov 2016

Molecular Hydrogen Complexes of Mo and W

Submitted by Kyle Grice, DePaul University
Evaluation Methods: 

Students will be evaluated with in-class participation and ability to work through the questions. 

Description: 

Literature discussion about the first examples of molecular hydrogen complexes isolated by Gregory J. Kubas in the early 80s. The questions are divided into groups with two levels of difficulty.

The more basic group of questions includes topics on:

1)      Coordination Chemistry: electron count, geometry, oxidation state, orbital interactions, types of ligands, binding modes, cis/trans and fac/mer isomers.

2)      Symmetry elements and point groups.

3)      Basic concepts on spectroscopy: NMR, Raman, IR, UV/Vis, XANES, EXAFS, neutron and X-ray diffraction

The more challenging group of questions include topics on:

1)      IR spectroscopy: fundamental vibrational modes, isotope effect

2)      Difference between η2 molecular hydrogen complexes and dihydride complexes.

3)      NMR spectroscopy: couplings, signal splitting and broadening, chemical shift

 

A supplemental question set has been included, which covers how to determine the 6 fundamental modes for the W(H2) portion of the entire molecule. This would be an advaned exercise, and notes for the instructor are also included.

Corequisites: 
Course Level: 
Learning Goals: 

After completing this exercise…

-Students will be able to recognize research that is important to the field

-Students will be able to assign oxidation state, coordination number, ligand characteristics, and 18-electron rule count for a metal complex

-Students will be able to consider various spectroscopic methods to studying complexes and reactions and what information can be obtained from them.

-Students will recognize the difference between X-ray diffraction and neutron diffraction

-Students will demonstrate the interactions between metals and ligands using frontier orbitals.

-Students will be able to assign point groups and use group theory to determine the number of IR and Raman-active vibrations for a molecule

Implementation Notes: 

Give students a copy of the paper and discussion questions ahead of time.

 
Modifiy the questions based on the level of students that are in your class and what material you wish to focus on. 
 
Another idea would be to give groups of students just some of the questions, have them answer them and then present the answers to the class.  
 
Use the visualizations provided by Marion Cass (see web resources) to help inform the discussion with your students. 
Time Required: 
Entire class period

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