This is a literature discussion based on a short paper on ethylene compounds of the coinage metals (Dias, H. V. R.; Wu, J. Organometallics 2012, 31, 1511-1517). In this paper, analogous ethylene compounds are prepared with Cu(I), Ag(I) and Au(I). The other ligand on the coinage metal is a scorpionate tris(pyrazolyl)borate ligand. The strength of the interaction between the metal and the ethylene varies significantly with the coinage metal as seen in X-ray crystallographic and spectroscopic (1H and 13C NMR) data. A particularly interesting feature is the 1H NMR spectra of these compounds under an atmosphere of ethylene in which the coordinated ethylene can exchange rapidly with the free ethylene.
After completing this literature disussion LO students should be able to
- recognize and count electrons for compounds with scorpionate tris(pyrazolyl)borate ligands
- explain how metals interact with the orbitals of an alkene
- describe the impact of the interaction of a metal with ethylene in terms of structural parameters and NMR data
- define coalescence and recognize how the rate of ligand exchange can impact the observed NMR spectrum
Students should read the paper before coming to class. I think I would see if they seek out the supporting information on their own rather than specifically hinting/suggesting/telling them to pay attention to it. Not having used this in class yet, my opinion on this could change.