Self-assembly synthesis of a [2]catenane Co(II) single-molecule magnet.

We describe herein the self-assembly synthesis of an octanuclear Co(II) [2]catenane {[Co4L6]2}16+ formed by the mechanical interlocking of two [Co4L6]8+ rectangles of unprecedented topology. Subtle manipulation of the synthetic conditions allows the isolation of a mixed valence [Co2III/Co2II]10+ non-catenated rectangle. The Co(II) centers in the [2]catenane exhibit slow relaxation of their magnetic moment, i.e. single-molecule magnet properties, dominated by quantum tunneling and Raman relaxation processes. This work shows that metallo-supramolecular chemistry can precisely control the organization single-molecule magnets in topologically complex arrangements.