Synthesis, crystal structure, and magnetic properties of a new tetranuclear Cu(II) Schiff base compound

A new tetranuclear Cu(II) compound [Cu4(HL)2(L)2(ClO4)2] (1) was synthesized from the reaction of Cu(ClO4)2 · 6H2O with Schiff base ligand (H2L) condensed from ethanolamine with 2-hydroxyacetophenone. X-ray diffraction studies revealed that 1 is formed from the self-assembly of two dinuclear units [Cu2(HL)(L)(ClO4)] through the doubly phenoxo bridging. The variable temperature magnetic susceptibility measurements were performed between 300 K and 2 K and show χMT value for 1 at 300 K is 1.395 cm3 mol−1 K and fall to 0.0459 cm3 mol−1 K at 2 K. These values are smaller than that expected for tetranuclear copper (II) units, indicating antiferromagnetic coupling present in the compound. This result is also confirmed from the DFT calculations.

Graphical abstractA new tetranuclear Cu(II) compound [Cu4(HL)2(L)2(ClO4)2] (1) was synthesised from the reaction of Cu(ClO4)2 · 6H2O with Schiff base ligand (HL2) condensed from ethanolamine with 2-hydroxyacetophenone. X-ray diffraction studies revealed that it is formed from the self-assembly of two dinuclear units [Cu2(HL)(L)(ClO4)] through the doubly phenoxo bridging. In the dinuclear unit two copper (II) atoms surrounded by HL− and L2− Schiff base ligands. So protonated and deprotonated forms of the same Schiff base ligand were present in the same structural unit.The variable temperature magnetic susceptibility measurements show χMT value for 1 at 300 K is 1.395 cm3 mol−1 K and fall to 0.0459 cm3 mol−1 K at 2 K. These values are smaller than that expected for tetranuclear copper (II) units, indicating antiferromagnetic coupling present in the compound. The same result is also evaluated from the DFT calculations.Figure optionsDownload full-size imageDownload as PowerPoint slide