Resumen de Coupling Molecular Modeling to the Traditional "IR-ID" Exercise in the Introductory Organic Chemistry Laboratory.
Heather Stokes Huby, Dale E. Vitale
This exercise integrates the infrared unknown identification ("IR-ID") experiment common to most organic laboratory syllabi with computer molecular modeling. In this modification students are still required to identify unknown compounds from their IR spectra, but must additionally match some of the absorptions with computed frequencies they generate from computer molecular models. They then use animation of the corresponding bonds in the model to obtain descriptions of the observed vibrations. This affords a vivid conception of the dynamic nature of covalent bonding that is not available from the traditional experiments. The computational exercises also provide students with a method for assigning IR absorptions to specific molecular vibrations when no reference is available. The animations also demonstrate the fundamental fact that all the bonds in a given molecule vibrate even if some of them do not absorb IR radiation. Suggestions are made for the types of compounds to be used and the computational software needed. Advice is also given on how to configure the experiments, computations, and networking so that time is not an issue. Emphasis is on the IR experiment, and a high level of computational chemistry expertise is not required.
