Rational Design of a Confacial Pentaoctahedron: Anisotropic Exchange in a Linear Zn^IIFe^IIIFe^IIIFe^IIIZn^II Complex.

Walleck, Stephan; Atanasov, Mihail; Schnack, Jürgen; Bill, Eckhard; Stammler, Anja; Bögge, Hartmut; Glaser, Thorsten

The first confacial pentaoctahedron comprised of transition metal ions namely ZnIIFeIIIAFeIIIBFeIIIAZnII has been synthesized by using a dinucleating nonadentate ligand. The face‐sharing bridging mode enforces short ZnII⋅⋅⋅FeIIIA and FeIIIA⋅⋅⋅FeIIIB distances of 2.83 and 2.72 Å, respectively. Ab‐initio CASSCF/NEVPT2 calculations provide significant negative zero‐field splittings for FeIIIA and FeIIIB with |DA|>|DB| with the main component along the C3 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 Jxy= 0.37, Jz=−0.32, DA=−1.21, EA=−0.24, DB=−0.35, and EB=−0.01 cm−1 supported by simulations of high‐field magnetic Mössbauer spectra recorded at 2 K. The weak but ferromagnetic FeIIIAFeIIIB interaction arises from the small bridging angle of 84.8° being at the switch from anti‐ to ferromagnetic for the face‐sharing bridging mode.

TRANSITION metal ions; AB-initio calculations; SUPRAMOLECULAR chemistry; TRANSITION metals; ELECTRONIC structure; MAGNETIC properties

Chemistry - A European Journal, 2021, Vol 27, Issue 61, p15239

0947-6539

Academic Journal

10.1002/chem.202102572