Mu (H) Atom Addition to Imidazol-2-ylidenes
Iain McKenzie, Jean-Claude Brodovitch, Paul W. Percival, Taramatee Ramnial and Jason A. C. Clyburne
Muonium has been used to determine which of two possible sites of addition is preferred when a hydrogen atom is added to imidazol-2-ylidenes. Muon spin rotation and muon level-crossing spectroscopy were used to determine muon, 13C and 14N hyperfine coupling constants (hfcs) for the radical products of addition to two different carbenes. Good agreement between the experimental and calculated hfcs confirms that Mu (and hence H) adds exclusively to the carbeneic carbon. The radicals that are produced have non-planar radical centers with most of the unpaired electron spin density localized on the alpha-carbon.