Simultaneous Introduction of Redox and Coordination Chemistry Concepts in a Single Laboratory Experiment

The preparation of two crystalline binary transition metal  p -toluenesulfonate salts of [M II (OH 2 ) 6 ][OTs] 2  stoichiometry, where M II  = Co (1) and Ni (2), is described. Their syntheses are accomplished via an oxidation–reduction reaction using metal powders and aqueous  p -toluenesulfonic acid hydrate as the reducing and oxidizing reagents, respectively. Over the span of one 4 h session, students learn concepts that include reaction stoichiometry, relative rates, complexation, crystal growth and isolation, and fractional crystallization methods. A second session allows for the origins of color and spectroscopy (UV–vis and infrared) to be investigated by more advanced students. Suitably equipped laboratories may also pursue independent student projects involving additional microscopy, X-ray solution and refinement, and magnetic susceptibility exercises.