Prof. David Procter and Dr. Michael Szostak, of U. Manchester in England, want you to think of it a lot more often. Their latest ACIEE explores some crazy stunts thulium diiodide can do when mixed with a little alcohol: Blowing apart esters. Reducing arenes. Unwrapping amides (see below):
All thanks to the extra reducing power of this "non-classical" lanthanide salt. At a good 50% more than samarium diiodide, thulium diiodide can inject a single electron into just about any C=O or arene around, and there's evidence that it slips into neighboring C-N bonds to promote fragmentation:
|Source: Szostak, ACIEE 2013|
Bill Evans (organometallics, not jazz) previously explored this reagent over a decade ago, marketing it as a souped-up SmI2 / HMPA. His study looked at cyclic ketones, which formed adducts with primary iodides in less than a minute with a healthy dose of TmI2(DME). Despite these exciting early results, it appears that thulium took a back burner to the samarium 'craze' of the mid-'00s, and only now gets its chance in the limelight.
Keep an eye out for more TmI2 reactions; after 100 years of new bond-forming reactions, it's nice to see trends to the contrary.
Update (6/14/13) - Added Prof. Procter and group website.
(6/14/13) - Changed lactam to amide - thanks, Anon!