Cover Feature: “Catch‐Store‐Release” Strategy for the Stabilization of 4,4′‐Methylene Diphenyl Diisocyanate (4,4′‐MDI) (Chem. Eur. J. 30/2023)

4,4’-Methylene diphenyl diisocyanate (4,4’-MDI) is a key linker in the production of polyurethanes. 4,4’-MDI thermally unstable, undergoing dimerization to unreactive and insoluble uretdione. The “catch–store–release” strategy presented Research Article by S. Groysman co-workers (DOI: 10.1002/chem.202300924) allows be stabilized form an imidazolium amidate that produced coordination two equivalents N-heterocyclic carbene. complex can released heating with CuCl (with or without sulfur); this forms CuI carbene/urea restores MDI. Artwork authors help from Mary Iverson.