Syntheses and thermal characterization of the magnesium phthalocyanine complexes with 2-methoxy- and with 2-ethoxyethanol. X-ray structure of (2-ethoxyethanol)magnesium phthalocyanine

The syntheses of the magnesium phthalocyanine complexes with dry 2-methoxy-ethanol and 2-ethoxyethanol have been performed by recrystallization method using both anhydrous MgPc and aquated magnesium phthalocyanine, MgPcH₂O, as a starting material. It has turned out that in the temperature range below ca. 140 °C, the bi-axially ligated complexes are formed, i.e., MgPc(2-methoxyethanol)₂ and MgPc(2-ethoxyethanol)₂ with 4 + 2 coordination of Mg, whereas at higher temperatures, up to about 200 °C, the mono-axially ligated complexes are stable, i.e., MgPc(2-methoxyethanol) and MgPc(2-ethoxyethanol) with 4 + 1 coordination of Mg.The single crystal structure of MgPc(2-ethoxyethanol) complex has been determined. The central Mg atom is displaced towards the hydroxyl group of the ligand by about 0.37 Å from the (N-isoindole)₄ plane of the Pc ring. Hydrogen bonds of the type O-H?N between the hydroxyl groups of 2-ethoxyethanol and one of the azamethine N-atoms of the Pc ring link the molecules related by a centre of symmetry. Such a packing arrangement in the crystal leads to a dimerization with the ligand-to-Pc connections. The syntheses, thermogravimetric results and structure characteristics are compared with the known MgPc complexes with O- and N-donating molecules.