Atropochiral C,X- and C,C-Chelating Carbon Ligands

In the realm of atropochiral ligands initiated by the BINOL and BINAP paradigms and extended by modifications of the 1,1'-binaphthyl backbone and the coordinating heteroatoms (O, P, N, S,..), the emerging domain of the carbon versions serving as spectator ligands in catalysis is reviewed. These atropochiral C,X-chelating ligands are classified according to their coordinating mode (monodentate or bidentate), to the nature of the auxiliary donor X (a heteroatom or a carbon atom), to the overall charge of the coordinating carbon function (neutral or anionic C-ligands), and to the hapticity of the coordinating carbon function (eta(1) for NHCs and ylides, or eta(2) for alkenes). Emphasis is put on both synthetic aspects and applications in catalysis, and especially in asymmetric catalysis. This survey suggests that the "carbon ligands" should continue to provide surprises not only in coordination chemistry and in stereoselective synthesis and catalysis, but also in fundamental molecular chemistry by pushing farther the stability limits of the metal ligand interactions, thus reconciliating further the fields of organic and inorganic chemistry.