1ST DIRECT SYNTHESIS OF A CORROLE RING FROM A MONOPYRROLIC PRECURSOR - CRYSTAL AND MOLECULAR-STRUCTURE OF 18-OCTAMETHYLCORROLATO)COBALT(III)-DICHLOROMETHANE

The first synthesis of the corrole ring by self-condensation of a mono pyrrolic unit is reported. The reaction occurs only in the presence of cobalt ions; it leads to the formation of (triphenylphosphine)(5,10,1 5-triphenyl-2,3,7,8,12, 13,17,18-octamethylcorrolato)cobalt(III), [Co( OMTPC)PPh3] and represents the first example of interconversion betwee n a porphyrinoid and a corrole structure. Crystals of [Co(OMTPC)PPh3]. CH2Cl2 have been obtained by slow diffusion of methanol into a dichlor omethane solution of the complex and have been characterized by single -crystal X-ray analysis. They crystallize in the triclinic system, spa ce group P1BAR, with a = 10.628 (2) angstrom, b = 11.585(2) angstrom, c = 22.352(4) angstrom, alpha = 84.93(2)-degrees, beta = 78.56(2)-degr ees, gamma = 72.93(2)-degrees, and Z = 2. The structure was solved by heavy-atom methods and refined by least-square techniques to R = 0.051 for 6377 unique data [F(o) > 4 sigma(F(o))]. The analysis reveals the substantial planarity of the macrocyclic ring. In the 23-atom core of the corrole moiety each atom shows an average displacement from the p lane of best fit of 0.14 angstrom, with the largest deviations being 0.33 and -0.33 angstrom for C(2) and C(12), respectively. The synthesi s of diphenyl derivatives of corrole: (triphenylphosphine) 3,7,8,12,13 ,17,18-octamethylcorrolato)cobalt(III), [Co(5,10-OMDPC)PPh3], and (tri phenylphosphine) 3,7,8,12,13,17,18-octamethylcorrolato)cobalt(III), [C o(5,15-OMDPC)PPh3], is also reported. Plausible reaction pathways lead ing to the formation of the two isomers are discussed together with th e spectral properties of the complexes.