Synthetic and structural studies on metal complexes of tripyrrin

A general two-step procedure for the synthesis of metallotripyrrinates TrpyMOAc(f) with M = Co(II), Cu(II), Zn(II) and Pd(II), and OAcf = trifluoroacetate, is described, starting from wellknown monopyrrolic precursors and simple transition metal acetates. X-ray structural investigations were undertaken on four different complexes, and the results reveal, that the nature of the metal ion, rather than the ligand, determines the coordination geometry of these porphyrin fragment complexes. The finding of pseudotetrahedral and strained pseudoplanar coordination polyhedra at the metal centres makes a clear distinction between metalloporphyrins and metallotripyrrins and shows the latter to be related to some recently discovered metal chelates of macrocyclic porphyrin analogues. Copyright (C) 2003 Society of Porphyrins & Phthalocyanines.