Discovery-Based Approach to Identify Multiple Factors That Affect the Spin State of Coordination Complexes Using the Evans NMR Method
Masaki Uchida, Candice H. Cortney, Karina Bustos, Elia Manzo, Emily Sauls, Jacob Bouchard, Risako Fukazawa, V. V. Krishnan
Abstract
Understanding the basics of d-electron configuration and the spin state of coordination complexes are essential elements of undergraduate inorganic chemistry. However, students in these courses find it difficult to conceptualize the ideas. Here, we have developed an undergraduate laboratory experiment that allows students to systematically evaluate the spin state of a set of coordination complexes composed of different ligands, metals, and the charge on a metal. Students assessed magnetic susceptibility and the number of unpaired electrons present on the metal centers of various complexes using the Evans method for NMR spectral data. They then identified the spin state of the complexes. Examining a series of complexes systematically leads students to discover three key factors that affect the spin state of coordination complexes: the type of ligand, the type of metal center, and the charge on the metal. A detailed description of the approach provided here can be implemented in inorganic and physical chemistry teaching laboratory settings.