A Metallocorrole with Orthogonal Pyrrole Rings

In contrast to sterically hindered metalloporphyrins, which are almost always strongly nonplanar, similarly substituted metallocorroles are generally relatively planar. A crystal structure of a copper β-octakis(trifluoromethyl)-meso-triarylcorrole, however, has revealed a corrole macrocycle with an unprecedented degree of saddling. With the exception of the bipyrrole unit, any two adjacent pyrrole rings are essentially orthogonal to each other. Furthermore, the C2-symmetric molecular structure is chiral and NMR spectroscopy and DFT calculations suggest that the enantiomers do not interconvert readily. Once resolved, the molecule may provide us with a novel example of an inherently chiral chromophore.