A chiral copper(II) inverse-9-metallacrown-3 complex: Synthesis, crystal structure, ferroelectric and magnetic properties

The reaction of phenyl 2-pyridyl ketoxime (PhPyCNOH) with Cu(NO3)2·3H2O in methanol results in the chiral trinuclear complex [Cu3(OH)(PhPyCNO)3(NO3) (CH3OH)]·(NO3) (1), which has been characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. The structure of 1 exhibits a triangle of Cu(II) ions, centered by a triply bridging hydroxo ligand and with three edge-bridging oximate groups from the three PhPyCNO− ions. Preliminary variable-temperature magnetic susceptibility studies reveal an antiferromagnetically-coupled system showing antisymmetric exchange. Complex 1 crystallizes in an acentric space group (P21) that belongs to a polar point group, which displays second harmonic generation response and ferroelectric behavior, and provides a new strategy for designing functional coordination complexes.