Structure and magnetic properties of a chiral dinuclear copper(II) complex assembled from a bpca− anion

A novel chiral dinuclear Cu(II) cluster [Cu2(bpca)(bpy)(H2O)(NO3)3] (1) (bpca− is the anion of bis(2-pyridylcarbonyl)amine and bpy is 2,2′-bipyridine), was synthesized and characterized. Single crystal X-ray diffraction analysis showed that the two Cu(II) ions in complex 1 are sitting in a distorted octahedral arrangement and bridged by the organic spacer bpca−. Hydrogen bonding links neighboring dinuclear units into a three-dimensional framework. Inversion crystallographic symmetry gives dimers as either Λ or Δ isomers. Racemization of complex 1 was confirmed by circular dichroism (CD) spectroscopy. The temperature dependence of the magnetic susceptibility for complex 1 in the range 2–300 K indicates the presence of ferromagnetic Cu⋯Cu exchange. The data fitting gave the magnetic coupling constant J = 8.08 cm−1.