Co-reporter:Brian J. Esselman;Nicholas J. Hill
Journal of Chemical Education 2016 Volume 93(Issue 5) pp:932-936
Publication Date(Web):February 10, 2016
DOI:10.1021/acs.jchemed.5b00815
Advances in software and hardware have promoted the use of computational chemistry in all branches of chemical research to probe important chemical concepts and to support experimentation. Consequently, it has become imperative that students in the modern undergraduate curriculum become adept at performing simple calculations using computational software, interpreting computational data, and applying computational data to explain chemical phenomena. We utilize computational chemistry in a high-enrollment (>1200 students/year), undergraduate organic chemistry laboratory course in a manner similar to that of organic chemistry researchers. We have employed WebMO as a web-based, easy-to-use, and free front-end interface for Gaussian09 that allows our students to complete ab initio and density functional theory (DFT) calculations throughout the curriculum. Rather than an isolated exposure to computational chemistry, our students use computational chemistry to obtain a deeper understanding of their experimental work throughout the entire semester. By integrating calculations into the curriculum, the focus moves away from performing the calculations to providing insight into chemical phenomena and understanding experimental results. We provide here both an overview of the introductory laboratory experiment and our integrated approach.
Co-reporter:Brian J. Esselman;Nicholas J. Hill
Journal of Chemical Education 2015 Volume 92(Issue 4) pp:660-663
Publication Date(Web):January 16, 2015
DOI:10.1021/ed5002152
The electronic and molecular structure of the acylium cation ([CH3CO]+, 1) receives varied treatment in undergraduate textbooks and online resources. The overall structure of 1 is typically represented as an equal combination of resonance structures containing C–O triple and double bonds, the latter structure occasionally being shown with a bent C–C–O bond angle. This description is inconsistent with available experimental and theoretical data, all of which indicate that 1 is a linear molecule containing a C≡O bond, and can lead students to a false conception of structure, conjugation, and charge distribution. A set of simple computational exercises is reported that allows students to calculate and rationalize the most accurate resonance representation of 1.