The literature discussion is based on a paper by Legzdins (Organometallics, 2017, 36, 26). In this work, the C-H activation of methane by a [Cp*W(NO)(allyl)(alkyl)] compound is described. The paper is extremely well written and approachable for undergraduates, although the initial length and large quantity of experimental data might be a bit intimidating at first. The problem of using methane is a signifiant real world problem and as such should provide an interesting context to talk about this paper. The bonding of NO and allyl ligands is discussed as are a number of reactions in the process of converting methane to a larger ketone. These include C-H activation at a d0 compound (so it is not oxidative addition), CO insertion and an internal nucleohilic attack. Electron counting is an important component of this exercise. There is a large amount of spectroscopic data in the paper, but this LO only briefly examines the relationship between IR vibrations and electron density at the metal center and coupling to spin 1/2 nuclei that are less than 100% naturally abundant.
Upon completing this LO students should be able to
- Describe why the activation of methane is a significant problem that needs to be addressed
- Use the CBC method to count electrons in the tungsten compounds in this paper
- Describe the bonding in compounds with linear NO and η3-allyl ligands
- Outline the steps for the C-H activation of methane by this tungsten complex including a description as to why the C-H activation is not an oxidative addition
- Explain 183W satellites
Students should read the paper before coming to class. Although there are a lot of questions in the LO, if the students have done a good job reading the paper I would anticipate that they can get through them all. Certainly some of the questions can be left out, or perhaps only provide the students with a few of them before class. In particular, question 1 is about the big picture problem of methane transportation, and would likely be good for the students to do some research into this area before talking about the paper in class.
This paper was presented late in the fall semester and as such I was unable to use it in class. However, I will likely use it as the basis for my final. As a discussion I would envision collecting the answers to the questions that the students come up with jointly in class. I would also envision some component of their grade being based on participation.