In recent years, N-heterocyclic carbenes (NHC) have proved to be a versatile class of spectator ligands in homogeneous catalysis. Being robust anchoring functions for late transition metals, their ligand donor capacity and their molecular shape is readily modified by variation of the substituents at the N-atoms and the structure of the cyclic backbone. After the first attempts to use chiral NHC ligands in asymmetric catalysis in the late 1990's, which initially met with limited success, several novel structural concepts have emerged during the past two years which have led literally to an explosion of the field. With a significant number of highly selective chiral catalysts based on chiral NHCs having been reported very recently, several general trends in the design of new NHC-containing molecular catalysts for stereoselective transformations in organic synthesis emerge.

Coupled Copper Surface States Periodic arrays of quantum dots can create new electronic states that arise from coupling of the states created by confinement. Lobo-Checa et al. (p. 300 ) show that the electronic surface-state of copper can be converted into a regular array of quantum dots. An organic overlayer that is created on the copper surface has pores 1.6 nanometers in diameter that trap the surface states. The coupling of these trapped states is revealed in photoemission experiments, in which a shallow dispersive electronic band is formed.

Isomerize and polymerize! Thermally induced tautomerization of the N‐heteropolycyclic 1,3,8,10‐tetraazaperopyrene to a Wanzlick‐type carbene intermediate on a Cu(111) surface leads to covalently linked polyaromatic chains, which can be mechanically manipulated. The pictures show the respective structures superimposed on the STM images.

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