Regioselective β-metalation of meso-phosphanylporphyrins.: Structure and optical properties of porphyrin dimers linked by peripherally fused phosphametallacycles

meso-Diphenylphosphanylporphyrins were successfully prepared via Pd-catalyzed C-P cross-coupling reaction of the corresponding meso-iodoporphyrins with diphenylphosphane. The meso-phosphanylporphyrins underwent regioselective metalation at the beta carbon to produce novel classes of porphyrin dimers linked by peripherally fused phosphametallacycles. A Pd-mononucler complex was structurally characterized by X-ray crystallography, which revealed a flat structure of the Pd-linked porphyrin pi systems. Both experimental and theoretical results demonstrate that the orbital interaction between the pyrrolic p pi orbitals and the metal d pi orbital affects optical and electrochemical properties of the metal-linked coplanar porphyrin dimers.