Supramolecular Hybrid Complexes Based on Octahedral Molybdenum(II) Iodide Cluster and Zinc(II) Porphyrin.

The possibility of the formation of supramolecular hybrids based on two photosensitizers, an octahedral molybdenum(II) iodide cluster with six terminal isonicotinate ligands (Bu₄N)₂[{Mo₆I₈}(OOC–C₅H₄N)₆] (PyMoC, C) and A₄-type zinc(II) porphyrin (ZnTPP, P), has been demonstrated. Spectrophotometric and NMR titration methods have shown that the formation of CP_n complexes (n = 1–6) occurs in solutions of noncoordinating chlorinated solvents due to the formation of metal–N-ligand coordination bonds between the components. The use of an octahedral cluster as a hexatopic N-ligand and the lability of the Zn···N_Py bonds together lead to the formation of a series of CP_n complexes (n = 1–6), which are in dynamic equilibrium in solution. Nevertheless, conditions have been selected to isolate single crystals of individual forms CP_{4 + 2} and CP_{6 + 2}, and their structures have been determined by X-ray diffraction analysis. The PyMoC cluster turns out to coordinate four or six ZnTPP molecules, respectively, while both structures contain two "extramolecules" of zinc(II) porphyrin bound to the cluster via hydrogen bonds involving the oxygen atoms of the isonicotinate groups and protons of water axially coordinated to the porphyrin metal center. [ABSTRACT FROM AUTHOR]