This is a great new textbook by George Luther III from the University of Delaware. The textbook represents the results of a course he has taught for graduate students in chemical oceanography, geochemistry and related disciplines. It is clear that the point of the book is to provide students with the core material from inorganic chemistry that they will need to explain inorganic processes in the environment. However the material is presented in such a clear, logical fashion and builds so directly on fundamental principles of physical inorganic chemistry that the book is actually applicable to a much broader audience. It provides a very welcome presentation of frontier orbital theory as a guide to predicting and explaining much inorganic chemical reactivity. There are numerous very helpful charts and tables and diagrams. I found myself using the book for a table of effective nuclear charges when I was teaching general chemistry last semester. The examples are much more interesting that the typical textbook examples and would be easy to embellish and structure a course around. There is also a helpful companion website that provides powerpoint slides, student exercises and answers. The book covers some topics not typically seen in inorganic textbooks like the acidity of solids but the presentation of this information makes sense in light of the coherent framework of the text. We so often tell our students "structure dictates function". This text really make good on that promise. My only complaint is that I wish the title were something more generic so that I could use it for a second semester of introductory-esque material that we teach after students have taken a single semester of intro chem and two semesters of organic chemistry. So much of what is covered in this textbook is precisely what a second semester sophomore chemistry major should know before proceeding on in the major. But the title makes the book hard to sell to chemistry majors and that is regrettable.
This Guided Literature Discussion was assigned as a course project, and is the result of work originated by students Stefanie Barnett and Katelyn Yowell. It is based on the article “Synthesis, Electrochemistry, and Reactivity of Half-Sandwich Ruthenium Complexes Bearing Metallocene-Based Bisphosphines”, Shaw, A.P.; Norton, J.R.; Bucella, D.; Sites, L.A.; Kleinbach, S.S.; Jarem, D.A.; Bocage, K.M.; Nataro, C. Organometallics 2009, 28, 3804-3814. It includes a Reading Guide that will direct students to specific sections of the paper emphasized in the discussion. This article presents the study of an array of metallocene-based bisphosphine ligands.
After reading and discussing this article, a student should be able to…
- Understand the nomenclature of metallocene-based bisphosphine ligands.
- Apply the CBC electron-counting method in the presence of metallocene-based bisphosphine ligands, which may be in an oxidized form.
- Appreciate the role of phosphine cone angles in organometallic synthesis.
- Understand the effect of a ligand’s electron donor ability on a metal’s redox potential.
- Appreciate how synthetic methods may emphasize either the kinetic or thermodynamic product.
- Understand how 1H NMR can help differentiate dihydride/dihydrogen isomers.
This was developed after the semester in which I teach this material. I look forward to using it next fall and I hope to post some evaluation data at that point.
This literature discussion is based on one of early papers detailing the mechanism for the Monsanto acetic acid process (J. Am. Chem. Soc., 1976, 98, 846). In this communicaiton the identification of key intermediates in this process is carried out using infrared spectroscopy. While the paper is an easy read, there are lots of subtle points that can be brought out by asking the right questions which hopefully this LO does. Although we have plenty of excellent LOs asking students to identify the individual steps in the catalytic mechanism, this LO takes a slightly different approach and marches students through the mechanism.
Upon completing this LO students should be able to
- Use the CBC method to count electrons in the rhodium compounds in this paper
- Describe the bonding interaction between a metal and a terminal carbonyl ligand
- Identify the various reactions taking place in the Monsanto acetic acid process
- Relate data from IR spectroscopy to the bonding interaction between a metal and a ligand and to the identification of intermediates in this process
A literature discussion has been developed for two courses: (i) a more basic set of questions appropriate for a sophomore level course or, possibly, a one semester upper level course that does not spend much time on organometallics, and (ii) an in-depth, in- and out-of-class set of assignments appropriate for an organometallics unit or course. Both sets of questions explore the mechanism of olefin metathesis in first- and second-generation Grubbs catalysts using a variety of spectroscopic kinetic techniques that were presented in the paper Sanford, M. S.; Love, J. A.; Grubbs, R. H. J. Am. Chem. Soc. 2001, 123, 6543-6554 (doi: 10.1021/ja010624k).
A student should be able to do the following after completing this LO:
Identify and discuss the importance of an olefin metathesis reaction.
Distinguish between Fischer- and Schrock-type carbenes and count electrons in complexes featuring these ligands.
Predict Ia vs. Id mechanisms based on electron counting.
Discuss why 31P and 1H NMR, and UV-Vis, were appropriate spectroscopic techniques for measuring kinetics in these systems.
Explain how variations in the catalyst (halide, carbene substituent, phosphine substituent, phosphine vs. NHC, etc.) affect ligand exchange.
Describe why the second-generation catalysts outperform the first-generation catalysts based on olefin binding vs. phosphine loss (in contrast to the historical reasons for their design), and why trans- effect arguments do not apply to the Grubbs system.
Two of us ran portions of these (they were not complete) in Fall 2016. Both of us noted that students were confused by the NHC representation in the manuscript because the authors assume that the reader knows there is no H on the carbene carbon, yet one would predict a H there based on the line structure formalism.
It is important to point out to students that the work here represents only the first 1-2 steps of the overall mechanism of olefin metathesis. There is a question in both the basic and advanced exercises that has students analyze the metallacyclobutane intermediate, but this species is formed later in the mechanism than any of the work presented here.
This LO was used in class to help a student guide a discussion of the paper. We did not cover all of the LO in a 75 minute class period, as we let the discussion take us where it wanted to.
A better way to ensure student preparation would be to collect the questions at the beginning (or end, if they wanted to use their notes in class) of class to ensure that they had really studied the paper.
I used this LO as a guided reading handout and did not collect the answers so I do not have any assessment data at this time.
My students found this paper to be highly readable and very clear. It is dense, with a lot of information presented, but once the students dove in, we were able to discuss it at a high level.
This literature discussion is based on a paper by Karen Goldberg (J. Am. Chem. Soc., 1995, 117, 6889-6896). In this early paper by Goldberg, she studied the reductive elimination of ethane and methyl iodide from dppePtMe3I. The paper is well written, and approachable for undergraduates. It shows a real, interesting application of thermodynamic and kinetic methods to the study of a problem in mechanistic chemistry. The experimental details are complete, and this paper would serve as a good review of kinetics, thermodynamics, and organometallic reaction mechanisms.
This LO presents a series of guided reading questions that help a student approach some of the material presented in the paper in a more thorough way. It asks students to derive equations and understand how experimental data can be combined into a reaction coordinate free energy diagram. The LO is suitable for junior or senior undergraduates in an organometallics course or unit within an inorganic course.
An update and correction was made to the LO in April 2018. Questions 7 and 8 in the learning object have students address the point of the differing M-C and M-I bonds. For the purposes of understanding what was written at the time, the questions are still valid, but the conclusions drawn in the paper about M-X bond strengths are not. For more information, see the "faculty only" file entitled "Goldberg Update 201804."
upon completing this LO students should be able to
1. demonstrate where thermodynamic parameters come from in a reaction coordinate free energy diagram
2. derive complex rate equations using the steady state approximation
3. describe the principle of microscopic reversibility
4. gain a deeper appreciation for the experimental methods (thermodynamic and kinetic) used in mechanistic chemistry
I used this LO as a guided reading handout for a senior-level organometallics class. The questions and the paper were provided to the students a week in advance and the in-class activity was a student-led discussion of the paper.
I had the students prepare for the discussion before class by reading the entire article. Students then answered the guiding questions in small groups during a class period.
I graded this assignment based upon class participation. All 33 students participated in the discussion.
The average grade on this assignment was an A. Students very much enjoyed reading an article from the literature and connecting it to topics we discussed in class. This article opened up our discussion on catalysis and mechanisms. The article nicely describes the rational design of experiments to probe and catalytic reaction.
Good paper to introduce kinetics and mechanistic studies.
Reading and understanding a journal article is a critical skill to obtain as a student. After college, many students will pursue careers in which learning occurs exclusively from the literature. Students will read a full paper from the journal Inorganic Chemistry and answer guiding questions pertaining to the article. There will be an in class discussion about the article to introduce which is used to introduce the topic of catalysis. This assignment breaks down the article through a series of questions that helps students to navigate a journal article.
Students will look copper complexes which catalyze atom transfer radical addition (ATRA) under sustainable means.
The citation is Inorganic Chemistry 2012, 51, 11917-11929.
- Read a full journal article pertaining to organometallic chemistry
- Critically think about the chemical literature
- Read about and understand organometallic mechanistic and kinetic studies
- Determine that structural and electronic ligand modification influences the reactivity of catalysts
- Describe spectroscopic methods used to obtain rate constants
- Distinugish between coordinating and non-coordinating anions and effects on catalysis
- Define inner and outer spehere electron transfer and relate this to the proposed reaction mechanism
- Explain the mechanistic studies done to probe the lability of the TPMA ligand
I conducted this with a class of senior and junior chemistry majors and it went very well! This is a very long article so you could break this up into more basic topic and then more challenging ones.
Some of these questions could also be used on an exam.
The questions are doable as students in the course actually helped develop these questions. I broke the article up into sections and assigned each section to a group of 4 students who were required to develop at least two questions per section. I then helped form the questions with the students. This model worked well and may be of interest to other people in the community.
But this assignment can be delivered as is - as a literature assignment with the focus on electron transfer, catalysis, mechanistic studies, and kinetics.
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.
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 5 slides about introduces the term "atom economy" as a means for undergraduates to start thinking about the efficiency of synthetic reactions. While this term may not be the best measure of the overall process of a reaction (as it ignores other factors such as solvents and materials used in purification), it provides a nice introduction to a concept on green chemistry. An example of an atom economic reaction, hydroamination, is briefly highlighted as it is an important ongoing research area. Notes for the instructor are included in the slides.
Students should be able to:
- define atom economy and use it to assess the efficiency of a reaction
- explain the hydroamination reaction and the strategies involved to facilitate the reaction with a metal catalyst
- describe the bonding of metal-imido bonds and metal-pi-C=C bonds
Calculation of atom economy or drawing of molecular orbitals of the bonds involved could be a useful classroom activity. The mechanisms presented are selected examples that have been simplified, and one should keep in mind that other mechanisms exist, as well as other metals.
Some or all of the student answers may be collected for grading. One or more of the application questions may be used as a quiz/exam question. Instructor should also observe the students as they work and determine whether they are understanding the important points as they progress through the activity; be prepared to step in to assist.
This activity has not yet been used in the classroom.
Based on the literature reference, this activity allows students to discover inner-sphere and outer-sphere catalytic hydrogenation mechanisms then apply their knowledge to hydroborylation. This is a guided-inquiry in-class activity that students can complete in small groups or individually with instructor support.
The student will be able to...
1. Compare and contrast mechanisms for inner- and outer-sphere catalytic hydrogenation.
2. Predict behavior of more polar and less polar substrates.
3. Compare H2 to E-H as a substrate.
4. Compare hydrogenation to hydroborylation with respect to mechanisms.
This activity is intended to be used in class by small groups of students. They may or may not have previously read the JACS paper on which it is based, but they should have some understanding of: organic chemistry, metal atom oxidation states, coordination numbers, basic types of organometallic reactions (oxidative addition/reductive elimination). If the activity requires more time than the class period, or by instructor choice, one or more of the final application questions can be assigned as homework/used as exam questions.
Note that all ligands in the catalytic cycles are assumed to be "L" type.