Structural characterisation of beryllium phthalocyaninato(2-) complexes axially ligated by O- and N-donating ligands

Recrystallisation of beryllium phthalocyanine (BePc) in water-free 2-picoline (2-Mepy) and in water-free 3-picoline (3-Mepy) yields to obtain the BePc(2-Mepy)·2-Mepy (I) and BePc(3-Mepy)·3-Mepy (II), while recrystallisation in wet (containing water) 2- and 3-picolines isomers yields to formation of the aquaberyllium phthalocyaninato(2-) complexes that crystallise with solvent molecule, 2-picoline (Ia) or 3-picoline (IIa). Single crystal analyses show 4 + 1 coordination of the Be(II) ion in these complexes. It is equatorially ligated by the four N-isoindole atoms of Pc macrocycle and axially by the N-ring atom of 3-Mepy (II) or by O atom of water in Ia and IIa. Interaction of the central Be(II) ion of the BePc with axial N or O donating ligands leads to the saucer-shape form of Pc macrocycle and deviates the Be(II) from the N4-isoindole plane by ∼0.31 Å. Thus, π–π interaction between the π-clouds of Pc aromatic macrorings in II and additionally the O–H⋯N hydrogen bonds in Ia and IIa are the forces responsible for the stabilisation of the molecular arrangement in the crystals. Thermogravimetric analyses confirm the compositions of the complexes.