IMes-acac: hybrid combination of diaminocarbene and acetylacetonato sub-units into a new anionic ambidentate NHC ligand.

The mesoionic 5-acetylimidazolium-4-olate serves as precursor for an anionic, hybrid NHC, "IMes-acac", consisting of fused diaminocarbene and acetylacetonato units, whose respective coordination abilities are evaluated by the formation of a series of representative copper(I) complexes illustrating the ambidentate character of the ligand.