Covalently-linked Supramolecular Dimers of {Mn₂(μ-O)}²⁺ Complexes

A. Diodati, W. Chao, S. Hill, and G. Christou

University of Florida, Florida State University

Recent research in our group has included the synthesis and study of covalently-linked oligomers of manganese-oxo complexes of different types as potential spin-based molecular components in new 21^st-century technologies. Following our many reports of dimers and tetramers of the [Mn₃O(O₂CR)₃(mpko)₃]⁺ single-molecule magnets (SMMs) with an S = 6 ground state covalently-linked by dicarboxylate or dioximate linkers, which proved a wonderful resource for the study of quantum properties such as exchange-biased quantum tunneling of magnetization and quantum superposition/entanglement states, we have now also expanded this work to oligomers of other magnetic units. The latter has included dinuclear Mn^IIIMn^IV-oxo complexes with an S = ½ ground state, since we were unaware of any reports of the successful synthesis of supramolecular oligomers of such systems with only a single bridging dicarboxylate, our preferred linkage approach. We have thus identified and synthesized an attractive {Mn₂(μ-O)}²⁺ starting complex for our purposes and explored its linkage into dicarboxylate-bridged dimers using the ligand-substitution methods developed with the Mn₃ SMMs, targeting weakly exchange-coupled intra-dimer interactions. This presentation shall describe the synthesis and study of the resulting family of [Mn₂]₂ dimers employing various types of dicarboxylate linkers.