The structure of μ-oxo dimer of aluminium(III) porphyrin: a theoretical study

The gas-phase molecular structure of μ-oxo dimer of aluminium(III) porphyrin, (AlP)2O, has been studied for the first time by density functional theory calculations using the B3LYP and M06 functionals and triple-ζ valence basis sets. The molecule has two conformers with equilibrium structures of D4d and D4h symmetries with parallel macrocycles and aluminium-oxygen distances of 1.680–1.684 Å (M06/cc-pVTZ). The aluminium atom lies out of the plane of the four central nitrogen atoms and forms a square-based pyramid with them, with the following parameters (M06/cc-pVTZ): r(Al–N) = 2.030–2.031 Å, r(N···N) = 2.803–2.804 Å (the side of the pyramid base), z(Al)–z(N) = 0.434–0.446 Å (the height of the pyramid).