Heterocyclic Carbenes

New carbenes open up new vistas. The P-heterocyclic carbene 1 was obtained after planarization of the P atoms in the heterocycle with sterically demanding substituents. The cyclohexyl substituent in the cyclic alkylaminocarbene 2 can be locked by proper substitution in the most sterically demanding conformation such that a low-coordinate metal center, as in complex 3, is stabilized.