New Configurationally Stable Chiral Building Blocks for Polynuclear Coordination Compounds:  Ru(chiragen[X])Cl2

The two enantiomers (Δ and Λ) of Ru(chiragen[X])Cl2, where “chiragen” is a tetradentate ligand with a chiral bridging unit between two bipyridine moieties, have been prepared in high yields. X is m-xylyl (m-xyl); other bridging groups (e.g., −(CH2)5− or −(CH2)6−) behave similarly. This complex can be used as an enantiomerically pure building block for the synthesis of stereochemically well defined polynuclear species. As an example, all three isomers (ΔΔ, ΛΛ, and ΔΛ) of [(chiragen[m-xyl])Ru(bpym)Ru(chiragen[m-xyl])](PF6)4 were prepared and fully characterized by NMR and various other spectroscopic methods.