The π and σ bonding modes of meso-octaethylporphyrinogen to transition metals: the X-ray structure of a meso-octaethylporphyrinogen–zirconiuml(<scp>IV</scp>) complex and of the parent meso-octaethylporphyrinogen ligand

The meso-octaethylporphyrinogen tetraanion provides σ and π binding pyrrolyl anions to electron poor transition metals, as shown in the structure of the meso-octaethylporphyrinogen–zirconium(IV) complex containing two η5 and two σ metal-bonded pyrrolyl anions.