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.