The Study of Metal–Carbonyl Complexes by Means of Computational IR Spectra Analysis: A Remote Didactic Approach Based on Chemical Thinking

We describe a remote pedagogical approach based on chemical thinking to study metal–carbonyl complexes by analyzing simulated IR spectra. The proposed approach, implemented due to the COVID-19 pandemic, can be employed in classrooms that have very limited laboratory equipment for evaluating toxic metal–carbonyl compounds, as well as for synthesizing compounds that have not been reported. The method, consisting of a class lecture accompanied by a remote computational activity, aims to provide students with the ability to assemble concepts from different fields, such as organometallic chemistry and analytical chemistry, while taking advantage of computational methods to answer higher level questions. We evaluated whether analyzing the nature of M–CO bonding was appropriate for achieving these educational goals. Octahedral compounds of the M(CO)6 and M(CO)4L2 type, bearing a variety of metal centers (M = Cr, Mo, W, V, Mn and Fe) and ligands (L = phosphines and phosphites), as well as bimetallic Fe2(CO)9, were compared, showing how these modifications affect M–CO bonding. After the didactic session, attended by second-year and upper-division students of Facultad de Química at UNAM, an evaluation and survey showed that students improved their understanding of the subject when they obtained and visualized IR spectra, also exhibiting greater confidence and enthusiasm for addressing challenging topics. The combination of computational results, spectroscopic analysis, and organometallic theory represents an efficient and clear procedure for implementing chemical thinking, regardless of the difficulties posed by the COVID-19 pandemic.