Synthesis, derivatization and structural characterization of octahedral tris(5-phenyl-4,6-dipyrrinato) complexes of cobalt(III) and iron(III)

The formation of octahedral tris(5-phenyl-4,6-dipyrrinato) complexes of cobalt(III) and iron(III) of p-substituted (-H, -CO2Me, -NO2) 5-phenyl-4,6-dipyrrins is described. The molecular structure of the parent cobalt(III) complex was determined by X-ray crystallography. Crystals of C45H33N6Co . C3H6O are monoclinic, a = 13.539(2), b = 22.348(2), c = 13.467(1) Angstrom, V = 3882.7(8) Angstrom(3), Z = 4, space group C2/c. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R = 0.039 and Rw = 0.033 for 2309 reflections with I greater than or equal to 3 sigma(F-2). These regular octahedral complexes underline the special coordination properties of the 5-phenyl-4,6-dipyrrins as compared to alpha,beta-alkyl-substituted dipyrrins for which no such tris-complexes are known. The reduction of the p-nitro-substituted Co(III) complex to the corresponding p-amino complex and the saponification, chlorination and esterification of the p-methoxycarbonyl-substituted Co(III) complex are reported, highlighting the chemical stability of the complexes and their potential to be incorporated into larger structures. (C) 1997 Elsevier Science S.A.