27 Dec 2016

Binding dinitrogen to titanium sandwich compounds

Literature Discussion

Submitted by Chip Nataro, Lafayette College

The literature discussion is based on one of the early papers from the Chirik group (J. Am. Chem. Soc., 2004, 126, 14688). In this communication, the coordination of N2 to a series of (C5H4R)2Ti fragments is examined. Being a communication, it is very short and that helps make it less intimidating for undergraduates. But don't be fooled, it is very rich in the fundamental concepts of orgnaometallic chemistry. The nitrogen fixation reaction has real world significance and is therefore an interesting big picture idea to talk about in relation to this paper. The bonding of Cp ligands is discussed in the context of this paper. In addition, this paper also presents paramagnetic and dimagnetic Ti(II) compounds and thus provides an opportunity to discuss the characterization of paramagnetic compounds. The use of X-ray crystallography and IR spectroscopy in relation to the strength of a bonding interaction between ligands and a metal center is also discussed. Finally, there is an opportunity to apply group theory to determine the number of IR active bands in the IR spectrum of a carbonyl compound. The supporting info for this paper is such a key part of this LO that links to both the paper and the supporting info are included below. In addition, there is a link to a Hoffman paper detailing the MO diagram for Cp2M compounds which might prove useful in discussing the paramagentic and diamagnetic Ti(II) compounds.

File Questions for students18.99 KB
Learning Goals: 

Upon completing this LO students should be able to

  1. Describe why nitrogen fixation is a significant chemical reaction worthy of study
  2. Use the CBC method to count electrons in the titanium compounds in this paper
  3. Describe the bonding in compounds with Cp ligands
  4. Describe how a paramagnetic substance can be recognized when using standard characterization techniques and suggest other means of characterizing paramagnetic compounds
  5. Relate data from IR spectroscopy and X-ray crystallography to the bonding interaction between a metal and a ligand
Time Required: 
50 minutes
Evaluation Methods: 

This LO was developed after the course I would use it in had ended. I am looking forward to using it next year and I hope to post some evaluation results at that point.

Creative Commons License: 
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