Enantiomorphs of a carbene-ruthenium(II)-porphyrin complex with four 'chiral pillars'.

The chiral metalloporphyrin (dibenzoylmethylene-kappaC)(ethanol-kappaO){5,10,15,20-tetrakis[(1S,4R,5R,8S)-1,2,3,4,5,6,7,8-octahydro-1,4:5,8-dimethanoanthracen-9-yl]porphyrinato-kappa(4)N}ruthenium(II)-ethanol-dichloromethane (1/2/2), [Ru(C(84)H(76)N(4))(C(15)H(10)O(2))(C(2)H(6)O)].2C(2)H(6)O.2CH(2)Cl(2), and its enantiomorph were prepared from enantiomerically pure porphyrins. The enantiomers are potential versatile catalysts for asymmetric cyclopropanation, aziridination or epoxidation. In each compound, the rather large dibenzoylcarbene group is squeezed between four columnar 1,2,3,4,5,6,7,8-octahydro-1,4:5,8-dimethanoanthracen-9-yl groups at the meso positions resulting in a doming deformation of the porphyrin core. The dibenzoylcarbene group has an anti conformation. The benzoyl O atoms make short van der Waals contacts (< 2.6 A) with the methine groups of the chiral columnar substituents at the 10 and 20 positions of the porphyrin rings. A hydrogen-bonded supramolecular chain is formed parallel to the b axis by interactions between the benzoyl O atom and the hydroxy groups of the coordinated and uncoordinated ethanol molecules.