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

Article abstract of DOI:10.1016/s0020-1693(97)05700-9

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) A?, V=3882.7(8) A?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≥3σ(F²). These regular octahedral complexes underline the special coordination properties of the 5-phenyl-4,6-dipyrrins as compared to α,β-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.