Heptacopper(II) and dicopper(II)-adenine complexes: synthesis, structural characterization, and magnetic properties

Abstract

The syntheses, crystal structures, and magnetic properties of two new copper(II) complexes with molecular formulas [Cu₇(μ₂-OH₂)₆(μ₃-O)₆(adenine)₆](NO₃)₂·6H₂O (1) and [Cu₂(μ₂-H₂O)₂(adenine)₂(H₂O)₄](NO₃)₄·2H₂O (2) are reported. The heptanuclear compound is composed of a central octahedral CuO₆ core sharing edges with six adjacent copper octahedra. In 2, the copper octahedra shares one equatorial edge. In both compounds, these basic copper cluster units are further linked by water bridges and bridging adenine ligands through N3 and N9 donors. All copper(II) centers exhibit Jahn–Teller distorted octahedral coordination characteristic of a d⁹ center. The study of the magnetic properties of the heptacopper complex revealed a dominant ferromagnetic intra-cluster interaction, while the dicopper complex exhibits antiferromagnetic intra-dimer interactions with weakly ferromagnetic inter-dimer interaction.

Graphical abstract

Keywords:

• Heptacopper(II)
• Dicopper(II)
• Copper cluster
• Adenine complexes
• Magnetic properties

Acknowledgements

Thanks are due to the University of Aveiro and CICECO for financial support of this work. B.J.M. Leite-Ferreira acknowledges FCT for her post-doc grant SFRH/BPD/81113/2011. Research at the Oak Ridge National Laboratory’s Spallation Neutron Source and Center for Nanophase Materials Science was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, of the U.S. Department of Energy.

Disclosure statement

No potential conflict of interest was reported by the authors.