Synthesis, structural investigation and thermal stability of aqua magnesium(II) phthalocyanine adducts with 2-methoxyethylamine

Three new aqua magnesium phthalocyaninato complexes with 2-methoxyethylamine (MEA) in crystalline form have been obtained. The composition of the complexes depends on the crystallisation temperature. (MgPcH2O)2 · MEA (I) and (MgPcH2O)2 · 2MEA (II) were formed at about 170 °C and 80 °C, respectively, while room temperature (MgPcH2O)2 · 3MEA (III) was obtained. In all crystals the Mg atom is 4+1 coordinated, equatorially by four N-isoindole atoms of Pc ligand and axially by O atom of water molecule. The MgPc moiety is non-planar, the Mg(II) deviates by ∼0.5 Å from the N4-isoindole plane towards the oxygen atom of water molecule. The MEA molecules in the crystals interact via hydrogen bonds with coordinated water molecules of MgPcH2O. The arrangement of MgPcH2O and 2-methoxyethylamine molecules is determined by O–H⋯N and O–H⋯O hydrogen bonds and by π–π interactions. The thermogravimetric analyses show characteristic steeps responsible for the loss of MEA molecules (at lower temperature) and water (at higher temperature) and finally all the complexes transform into β-MgPc. From among the complexes only complex II exhibits an intense near-IR absorption band in the solid-state, while spectra in MEA solution are identical for all the complexes.