Stepwise Formation of Heterobimetallic Macrocycles Synthesized via the Weak-Link Approach

A new dissymmetric bis-hemilabile ligand with strong binding phosphorus moieties, weak binding thioether moieties, and weaker binding ether moieties has been synthesized to construct heterobimetallic Rh(I)- and Pd(II)-containing macrocycles. The metals are placed in either the phosphorus/thioether or the phosphorus/ether coordination pocket of the dissymmetric ligand by taking advantage of the stepwise synthetic control offered by the weak-link approach. The weak bonds of these isomeric intermediates are systematically broken through ligand substitution reactions to cleanly and selectively generate a variety of open, macrocyclic architectures.