Structures of a 2-Pyrenolato-Coordinated Gallium Porphyrin with an Additional 2-Pyrenol Bound via Hydrogen Bonding: The Oxygen Atom Coordinated to the Metal Center is Likely to Serve as an Efficient Hydrogen Bond

Abstract The structure of a 2-pyrenolato–coordinated gallium porphyrin complex incorporating an additional hydrogen-bonded 2-pyrenol molecule has been determined [monoclinic, a = 18.60720(10) Å, b = 15.74080(10) Å, c = 28.3753(2) Å, β = 106.9530(10)°, space group P2₁/c]. The additional 2-pyrenol molecule forms a hydrogen bond with the oxygen atom of the coordinated 2-pyrenol. The gallium ion (Ga³⁺) is five-coordinate, adopting a square-pyramidal geometry with four nitrogen atoms from the porphyrin ligand and one oxygen atom from the 2-pyrenolato ligand. The Ga–O bond distance is 1.8799(15) Å, which deviates from previously reported values for gallium porphyrins bearing oxygen-containing axial ligands. The introduction of 2-pyrenol imparts properties characteristic of pyrene, namely CH–π and π–π interactions.