Molecular analogue of the perovskite repeating unit and evidence for direct MnIII-CeIV-MnIII exchange coupling pathway

The perovskite manganites AMnO3 and their doped analogues A1–x B x MnO3 (A and B = main group and lanthanide metals) are a fascinating family of magnetic oxides exhibiting a rich variety of properties. They are thus under intense investigation along multiple fronts, one of which is how their structural and physical properties are modified at the nanoscale. Here we show that the molecular compound [Ce3Mn8O8(O2CPh)18(HO2CPh)2] (CeIII 2CeIVMnIII 8; hereafter Ce3Mn8) bears a striking structural resemblance to the repeating unit seen in the perovskite manganites. Further, magnetic studies have established that Ce3Mn8 exhibits both the combination of pairwise MnIII 2 ferromagnetic and antiferromagnetic exchange interactions, and the resultant spin vector alignments that are found within the 3-D C-type antiferromagnetic perovskites. First-principles theoretical calculations reveal not only the expected nearest-neighbor MnIII 2 exchange couplings via superexchange pathways through bridging ligands but also an unusual, direct MnIII–CeIV–MnIII metal-to-metal channel involving the CeIV f orbitals.