This is a two-week lab in which students synthesize and then characterize three Werner cobalt complexes using IR, UV/VIS and computer calculations using Spartan. Syntheses are based on procedures from:
Angelici, R. J. Synthesis and Technique in Inorganic Chemistry. University Science Books, 1996, pp 13-17.
Borer, L.L.; Erdman, H.W.; Norris, C.; Williams, J.; Worrell, J. Synthesis of trans-Tetraamminedichlorocobalt (III) chloride, Inorganic Syntheses, Vol 31, 1997, pp 270-271.
Slowinski, E.; Wolsey, W.; Rossi, R. Chemical Principles in the Laboratory 11th ed. Cengage Learning, 2016.
Students were randomly assigned to synthesize one of the three Co complexes in week 1, and then worked in groups to characterize their complexes in week 2.* They were also required to compare the results for their complex with students in other groups. This latter process was partially completed in lab, and then student data was collected in a shared folder on Google Drive to allow all students access to data that they did not personally collect while writing their lab reports.
* In my iteration of this lab, students also measured the kinetics of aquation of the three complexes, with and without solid state catalysts. That portion of the lab still requires optimization, and was removed for simplicity. See instructor notes for a more thorough discussion.
Students will be introduced to models of bonding in coordination complexes using Werner's cobalt ammine complexes.
Each student will synthesize one cobalt ammine complex, and analyze the product using UV/VIS and IR spectroscopy.
Students will also carry out computations using Spartan to predict the spectra, view the molecular orbitals, and visualize IR vibrational modes for the molecule, and will compare this data to their experimental results.
A list of chemicals and equipment required is given in the prep notes (assuming a class of 12 students).
See Instructor notes document.