This literature discussion is based on a short JACS communication reporting the first isolable Sc(II) carbonyls (not a typo) and isocyanides.  The paper discusses some standard synthesis and characterization while exploring a more fundamental question regarding why Sc, a d-block metal, is considered a rare-earth and when it stops reacting analogously to the rare-earth metals.  The LO focuses on ye olde carbonyl stretching frequencies and back-bonding and makes a nice follow up to an introduction to that concept.  It tries to make students explicitly connect electron configuration to changes in IR frequencies, and how this can stops working when the valence electrons occupy f orbitals rather than d orbitals.