Synthesis and characterisation of dipyridinated magnesium phthalocyaninato(2-) complex

Abstract

A new complex of dipyridinated magnesium phthalocyanine has been synthesised in crystalline form by dissolving magnesium phthalocyanine in pyridine and heating at 160 °C. The crystals are formed during the slow cooling process. MgPc(py) 2 crystallises in the monoclinic system, space group P2 1/ c with two molecules in a unit cell. The structure was solved by direct and Fourier difference methods and refined by full-matrix least-squares techniques to R=0.0462, wR=0.1210 and S=1.012 for 3856 independent reflections and 242 refined parameters. The magnesium cation coordinates four isoindole nitrogen atoms of the almost planar phthalocyaninato(2-) ligand and axially two nitrogen atoms of pyridine molecules. The coordination polyhedron around the magnesium atom approximates to a tetragonal bypyramid with relatively long bonds between the Mg atom and the axial base ligands. The thermal analysis shows that the crystals of MgPc(py) 2 are stable up to ∼180 °C, at higher temperature the release of pyridine ligands is rapid. The UV–Vis and FT–IR and Raman spectra of MgPc(py) 2 are discussed in relation to its structure and compared with the spectral data of magnesium phthalocyanine.