Synthesis, characterization, and x-ray structure of the ruthenium “picnic-basket” porphyrins

The synthesis and characterization of a new class of sterically protected porphyrins, the “picnic-basket” porphyrins, are presented. These tetraarylporphyrins, which were prepared as cytochrome P-450 active-site analogues, bear a rigid superstructure on one face of the porphyrin macrocycle. The cavity defined by the appended superstructure may be readily varied in size, chirality, and functionality. In addition, the synthesis and characterization, including an X-ray structure, of several ruthenium picnic-basket porphyrin carbonyl complexes are reported. The regiochemistry of axial ligation in these ruthenium derivatives has been determined by NMR spectroscopy.