Platinum(II) Compounds with Enantiomerically Pure Bis(pinene)-Fused Bipyridine Ligands − Diimine-Dichloro Complexes and Their Substitution Reactions

The synthesis of chiral square-planar PtII complexes using symmetrical and unsymmetrical bis(pinene)-fused 2,2′-bipyridine is described. The neutral diimine dichloro complexes show a strong deviation of the coordination sphere from planarity if the pinene groups are attached at the 5- and 6-positions of the pyridine rings. However, this distortion does not occur in parallel with the chiral configuration at the diimine ligands. The substitution of the two cis-chloro ligands with diamines to form five-membered chelate rings shows little diastereoselectivity when racemic mixtures of chiral diamines are used. Also, ligands that are prochiral at the ligating centers show little selectivity upon coordination.