Chiral Molecules Containing Metal–Metal Bonds

Many chiral compounds having metal–metal bonds are now known in which the M–M unit is the chromophore. In this review they are classified as those where it is either (1) an inherently chiral chromophore owing to helical stacking of metal–ligand bonds, or (2) not inherently chiral but surrounded by a collection of ligands bearing chiral substituents. In only a few cases have the actual CD and/or ORD spectra been measured and analyzed. These include M 2 X 4 (PP) 2 molecules (PP = a bridging diphosphane) and M 2 (O 2 CR) 4 molcules where R is chiral. The more recently discovered helical extended metal atom chain (EMAC) molecules are also mentioned. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)