SYNTHESIS, CHARACTERIZATION, AND VARIABLE-TEMPERATURE H-1-NMR AND F-19-NMR INVESTIGATIONS OF CERIUM(IV) DOUBLE-DECKERS DERIVED FROM MONOFUNCTIONALIZED TETRAARYLPORPHYRINS

The synthesis of a cerium(IV) bisporphyrinate lb starting from (p-hydroxyphenyl)tris(p-tolyl)porphyrin 2b is described. Derived from 2b by substitution of the phenolic OH group, the monofunctionalized tetraarylporphyrins 2c-f and their cerium(IV) sandwich complexes lc-f were synthesized. The complexes are characterized by UV/Vis, IR, and H-1-NMR spectroscopy. F-19-NMR spectra of If show the presence of a vicinal and a transversal isomer due to the rigid square-antiprismatic coordination geometry of cerium(IV) bisporphyrinates. Variable-temperature H-1- and F19-NMR spectra were recorded to investigate the rotational rigidity of the double-decker system. The spectra show that the vicinal and transversal isomers are stable up to 140-degrees-C, i.e. rotation of the two porphyrin macrocycles with respect to each other does not occur.