PUB - Publikationen an der Universität Bielefeld

The first confacial pentaoctahedron comprised of transition metal ions namely Zn II Fe III A Fe III B Fe III A Zn II has been synthesized using a dinucleating nonadentate ligand. The face-sharing bridging mode enforces short Zn II Fe III A and Fe III A Fe III B distances of 2.83 and 2.72 A, respectively. Ab-initio CASSCF/NEVPT2 calculations provide significant negative zero-field splittings for Fe III A and Fe III B with \ D A \ > \ D B \ with the main component along the C 3 axis. Hence, a spin-Hamiltonian comprised of anisotropic exchange, zero-field, and Zeeman term was employed. This allowed by following the boundary conditions from the theoretical results the simulation in a theory-guided parameter determination with J xy =+0.37, J z =-0.32, D A =-1.21, E A =-0.24, D B =-0.35, and E B =-0.01 cm -1 supported by simulations of high-field magnetic Mossbauer spectra recorded at 2 K. The weak but ferromagnetic Fe III A Fe III B interaction arises from the small bridging angle of 84.8° being at the switch from anti- to ferromagnetic for the face-sharing bridging mode. © 2021 Wiley-VCH GmbH.