Hans Bruns, Mahendra Patil, Javier Carreras, Arcadio Vázquez, Walter Thiel, Richard Goddard, Manuel Alcarazo
Give me four: In contrast to typical imines, the central nitrogen atom in cyclopropenyl-derived carbeneimines (see example; C gray, N blue) can donate up to four electrons to form coordination complexes.
Angew. Chem. Int. Ed. 2010, 49, 3680; doi: 10.1002/anie.200906168