Metallostars containing {Ru(bpy)3} motifs

Two new ligands designed to act as the core for metallostars based upon multiple bpy (bpy = 2,2`-bipyridine) metal-binding domains have been prepared. The first ligand 6 consists of a 1,3,5-triazine bearing three bpy metal-binding domains and was prepared inter alia using Stille methodology. All attempts to form complexes of 6 were unsuccessful. In contrast, a non-planar core compound based upon a tetraphenylmethane moiety bearing four bpy domains, also prepared using Stille couplings, was shown to form a tetraruthenametallostar complex containing four Ru(bpy)(3) motifs. Each of the Ru(bpy)(3) motifs is chiral, possessing Delta or Lambda chirality and detailed NMR studies indicate that the complex is formed with little or no diastereoselectivity leading to a mixture of diastereomers and a fuzzy stereochemistry. (C) 2000 Elsevier Science S.A. All rights reserved.