11 Jul 2010

Organometallics and Named Reactions

In-Class Activity

Submitted by Laurel Goj Habgood, Rollins College
Categories
Description: 
A list of named reactions involving transition metal-complexes is provided to the class and the students present a brief overview of each which includes the original paper and a current application.
AttachmentSize
PDF icon Organometallics.pdf87.32 KB
Learning Goals: 
In the broader sense the learning goals of this assignment are to introduce the students to a variety of metal complexes and the synthetic utility available to organic chemists while developing their research and communication skills.  The specific learning goals are threefold.  Students will be able to use SciFinder Scholar to perform a basic literature search.  Students will practice their communication skills by creating the PowerPoint slides and delivering a short in-class presentation.  Students will be able to describe a named reaction starting with the substrate, the reagents used in the transformation, and the product pointing out the bonds that are broken/formed.
Equipment needs: 
A classroom with a projector.
Implementation Notes: 
I use this activity in both my second semester organic chemistry class as well as our foundational inorganic class when we reach the organometallic chapter.  For the organic students I try to compare and contrast the organometallic reagents with the classical organic methods they are learning.  For the advanced students I steer the discussion towards the choice of ligands, electron counting, and potential mechanisms.  The list of reactions is not exhaustive and can be added to or subtracted from based on class size or interest.
Time Required: 
Approximately 5 minutes per student. In a fifty minute class (second semester organic) approximately 9 students will finish and in a seventy-five minute class (foundational inorganic) approximately 10 students will finish.
Evaluation
Evaluation Methods: 
I do not explicitly grade the assignment but add it to the class participation points segment along the lines of a check plus, check, check minus system.  In the organic class a student earns a check if all the information is presented accurately and in a professional manner.  A student earns a check plus when additional connections are made such as differences/similarities between the original reaction and the later paper, whether the reactions are catalytic or stoichiometric, mentions the purpose of each reagent used, or makes a connection to a topic discussed in the glass.  The inorganic students are evaluated both on the presentation  (same as the organic students) and their ability to join in on the class conversation about the metals and ligands used as well as the mechanisms of the reaction.
Evaluation Results: 
All students are able to find the required papers although the organic students take longer to locate the papers and often consult our science librarian or stop by my office.   The presentations vary in quality in two ways:  quality of the slides and difficulty with the 5-minute time frame.  Some organic students have difficulty recognizing the fundamental transformation in the second paper.  This failure to transfer the knowledge from one reaction to another when the substrates are changed is common with weaker students.  I have observed that stronger organic students ask more questions as they make connections between the transformations/reagents in the presentations and the reactions studied in class.  For the inorganic students each presentation is a conversation starter.  After the presentation the student is questioned about the oxidation state of the metal, the ligands used, what might the potential mechanism be.  Students often have difficulty with the mechanisms and I use this assignment as a way of practicing this concept with problems not provided by the textbook.  The stronger students typically read the entire paper and are prepared to answer these questions for their presentation or offer help to the presenter who is struggling.   Students often make comments about the ease/difficulty of making these transition metal-complexes and the reaction conditions used.  I use this opportunity to try to make connections with their laboratory experiences.
Creative Commons License: 
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