Platinum(II) compounds with enantiomerically pure bis(pinene)-fused bipyridine ligands - Diimine-dichloro complexes and their substitution reactions

The synthesis of chiral square-planar Pt-II complexes using symmetrical and unsymmetrical bis(pinene)-fused 2,2'-bi-pyridine is described. The neutral diimine dichloro complexes show a strong deviation of the coordination sph ere from planarity if the pinene groups are attached at the 5-and 6-positio ns of the pyridine rings. However, this distortion does not occur in parall el with the chiral configuration at the diimine Ligands. The substitution o f the two cis-chloro ligands with diamines to form five-membered chelate ri ngs shows little diastereoselectivity when racemic mixtures of chiral diami nes are used. Also, ligands that are prochiral at the Ligating centers show Little selectivity upon coordination.