Regioselective beta-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 ppi orbitals and the metal dpi orbital affects optical and electrochemical properties of the metal-linked coplanar porphyrin dimers.