4+1 and 4+2 coordinated complexes of magnesium phthalocyanine with dioxane

Two complexes of magnesium phthalocyanine with dioxane were obtained. They co-crystallise in the centrosymmetric space group of the triclinic system. One of them is biaxially ligated (4+2) complex MgPc(dioxane)2 and the other is bridged μ-dioxane(MgPc)2. The interaction of the bridged dioxane molecule with two MgPc molecules is stronger than the interaction of two dioxane molecules axially ligated to the metal center of MgPc on the both sides of the Pc-plane. The strength of the MgO bond in these complexes correlates with their thermal stability. Owing to the Mg⋯O interaction of the bridged dioxane molecule with two MgPc units and formation of the μ-dioxane(MgPc)2 complex, the Mg atom is significantly displaced (0.357(3) Å) from the plane defined by four isoindole N atoms of Pc. This interaction causes a distortion of planar Pc(2-) macrocycle to the saucer-shape form. In biaxially ligated MgPc(dioxane)2 molecule the Pc(2-) macroring exhibits the planar form. Due to the steric hindrance of the axial ligand, the crystals exhibit better solubility than the parent MgPc, since the structure is less stabilized by π–π interactions between the aromatic Pc(2-) macrorings than in the structure of MgPc. Ligation of MgPc by dioxane does not change the colouring properties compared with the MgPc pigment. The calculated 3D molecular electrostatic potential maps are helpful for understanding the organisation and arrangement of molecules in the crystal.

Graphical abstractTwo complexes of magnesium phthalocyanine with dioxane MgPc(dioxane)2 and μ-dioxane(MgPc)2 were obtained. The complexes co-crystallise in the centrosymmetric space group of the triclinic system. Due to the steric hindrance of the axial ligand, the crystals exhibit better solubility than the parent MgPc. Ligation of MgPc by dioxane does not change the colouring properties compared with the MgPc pigment.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Two complexes of magnesium phthalocyanine with dioxane MgPc(dioxane)2 and (MgPc)2(dioxane) were obtained. ► Both MgPc(dioxane)2 and (MgPc)2(dioxane) complexes co-crystallise in the centrosymmetric space group of the triclinic system. ► X-ray analysis confirm the 4+2 and 4+1-coordination of Mg in biaxially ligated and bridged complexes. ► The steric hindrance of the axial ligand leads to better solubility than the parent MgPc. ► The 3D molecular electrostatic potential maps for reacted and the product molecules were calculated.