Model Coordination Complexes for Designing Poly(terthiophene)/Rh(I) Hybrid Materials with Electrochemically Tunable Reactivities

The synthesis and characterization of two chiral, redox-active Rh(I) bis(diphenylphosphinite) monomers, complexes 3 and 4, are reported. Complex 4, [(η 2 -1,2- bis(diphenylphosphinite),4-oxo-6-(3‘-α-terthiophene)Rh(I)(η 4 -C 7 H 8 )]BF 4, can be electrochemically polymerized to form poly- 4, and the η 4 -C 7 H 8 ligand can be hydrogenated in THF to form the metal-containing polymer 17 . Polymer 17 is proposed to consist of a poly(terthiophene) backbone with Rh(I) phenyl-bridged dimers acting as cross-linkers between neighboring polymer chains. This structural formulation for polymer 17 is based upon its electrochemistry and a comparison with the solution chemistry of monomer 4 . Significantly, this study discusses the importance of balancing polymerization potential, metal oxidation potential, and polymer ligating properties in the design of high surface area, polymeric, redox-switchable hemilabile ligands.