The complex structure of ferri-ferribactins

By comparison of the NMR data of the ferribactins from Pseudomonas chlororaphis ATCC 9446 and of P. fluorescens 18.1 with those of their Ga3+-complexes as models for the Fe3+-complexes it will be shown that only two bidentate ligands are provided for complexation, both located in the peptide chain. The two remaining free sites of the octahedral metal ion are probably occupied by solvent molecules.