21 Jun 2014

Properties of olefin complexes: Pt(II) vs Au(III)

Literature Discussion

Submitted by Margaret Scheuermann, Western Washington University
Categories
Description: 

This is a literature discussion based on a paper titled “Generation and Structural Characterization of a Gold(III) Alkene Complex” (Angew. Chem. Int. Ed. 2013, 52, 1660 - DOI 10.1002/anie.201209140) that reports the first crystallographically characterized Au(III) alkene complex, [(cod)AuMe2] [BArF]. The synthesis and characterization of [(cod)AuMe2] [BArF] are presented. The structural properties are compared to those of the isoelectronic species (cod)PtMe2, and to free cod. DFT calculations compare the contributions of metal and ligand orbitals in the Pt and Au cases, illustrating the greater importance of backbonding in the more electron rich Pt complex. This paper ties nicely into the course content when discussing backbonding and how olefins can coordinate to metal centers.

A set of guiding questions to prepare for an in class discussion is attached. Students complete the questions prior to class. Students were given about two weeks to work on the assignment.

AttachmentSize
Microsoft Office document icon lit_questions_VIPEr.doc222 KB
Learning Goals: 

After completion of the assignment students will have:

  1.  Developed an understanding of the relationship between the metal-olefin bond, and physical and spectroscopic properties of olefin complexes
  2. Read an article pertaining to organometallic chemistry

  3. Critically thought about the chemical literature

  4. Read about and understood the organometallic studies

  5. Attended an in class lecture related to topics presented in the paper

 

 

Implementation Notes: 

This assignment was used in the Spring 2014 inorganic reactions and mechanisms course at The College of New Jersey (TCNJ). Students read the paper and answered the questions before the class session. During class, students volunteered to share their responses, which were used as a starting point for the discussion. One of the paper’s authors (MLS) visited TCNJ to lead the discussion. Following the literature discussion “Five slides about Complexes of Alkenes, alkynes, and dienes” were presented to review what the students discovered from the literature activity.

The students at TCNJ pointed out that in Table 1 the C3-C4 and C7-C8 bond distance are nearly identical in the Pt and Au complexes. Other structures of (cod)PtMe2 with longer C3-C4 and C7-C8 bond distances have also been reported. See:

-Smith, D. C.; Haar, C. M.; Stevens, E. D.; Nolan, S. P.; Marshall, W. J.; Moloy, K. G. Organometallics 2000, 19, 1427.

- Klein, A.; Klinkhammer, K.-W.; Scheiring, T. J. Organomet. Chem. 1999, 592, 128.

Evaluation
Evaluation Methods: 

Students were evaluated by their participation in the discussion either by volunteering an answer or asking a question.

32 students participated in the class discussion and 31 of 32 students participated during the in class lecture given by Margaret. The grade for the assignment was out of 50 points. 10 points were assigned for class participation and 40 points were assigned for the questions. The average score on the overall assignment was 45/50 and the scores ranged from 28.5 (student didn’t participate in class) – 50. Students worked in teams of about 4 to complete the literature assignment. One assignment was submitted for each group prior to class. I may suggest allowing the students to resubmit responses after the in class lecture as some material may not be fully comprehended until the in class lecture. 

The students were very enthusiastic about the assignment and asked lots of questions about the article.

 

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