Synthesis, structure and magnetic properties of phosphate-bridged polynuclear copper(II) complexes

Three new phosphate-bridged copper(II) complexes, [Cu4(H2O)2(phen)4(μ4-PO4)2(μ2-O)]·11H2O (1), [Cu4(bpy)4(μ4-PO4)2(μ2-Cl)2]·18H2O (2) and [Cu2(bpp)4(H2PO4)2](HPO4)·H2O (3) (phen = 1,10-phenanthroline, bpy = 2,2-bipydine and bpp = 1,3-bis(4-pyridyl)-propane), have been synthesized under ambient conditions. The tetranuclear Cu(II) butterfly cores in 1 are aggregated to 2D supramolecular layer via intermolecular π–π stacking interactions. In 2, the dinuclear copper units are bridged by the phosphate and Cl− anion to generate centrosymmetric tetranuclear complex molecules [Cu4(bpy)4(μ4-PO4)2(μ2-Cl)2], which are aggregated to 2D layers via π–π stacking interactions. The Cu atoms in 3 are interlinked by a pair of bpp ligands to generate 2D (4,4) network which is through twofold ‘2D parallel/2D parallel’ mode inclined interpenetration to induce 3D motifs. The variable temperature magnetic characterizations suggest antiferromagnetic coupling interactions with J = −9.38 and −28.03 cm−1 for 1, J = −2.41 cm−1 for 2, respectively.

Graphical abstractThree new polynuclear copper(II)–phosphate complexes, [Cu4(H2O)2(phen)4(μ4-PO4)2(μ2-O)]·11H2O (1), [Cu4(bpy)4(μ4-PO4)2(μ2-Cl)2]·18H2O (2) and [Cu2(bpp)4(H2PO4)2](HPO4)·H2O (3) have been synthesized under ambient conditions. The magnetic characterizations suggest weak antiferromagnetic couplings for 1 and 2, respectively.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► 1 Represents a tetranuclear butterfly Cu(II) cores. ► 2 Exhibits a centrosymmetric tetranuclear Cu(II) units. ► 3 Adopts a twofold parallel interpenetrating sheets structure.