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Abstract:
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We present a density-functional theory study of the influence of ligand substitutions on the
geometric structure, electronic structure, and magnetic properties of Mn4 single-molecule magnets (SMMs),
in order to investigate the role of ligands in controlling these features, as well as in developing new SMMs
and single-chain magnets (SCMs). Our results show that the peripheral ligands play an important role in
controlling the magnetic ground-state of Mn4 SMMs. A new model is proposed to explain the spin state of
manganese ions in Mn4 molecules. This model shows that the saving energy from distortion, which can be
controlled by peripheral-ligand substitutions, plays a crucial role in determining the spin state of manganese
ions in Mn4 molecules. The mechanism of strong exchange couplings between manganese ions in Mn4
SMMs is revealed. The strength of exchange-couplings between manganese ions in Mn4 SMMs as a
function of their charge and spin state can be also controlled by substituting peripheral-ligands. The results
demonstrate the possibilities of developing new Mn4-based SMMs. In addition, strong spin polarizations on
peripheral ligands containing sp2-hybridized carbon sites show that using ligands containing sp2-hybridized
carbon sites can enhance exchange couplings between Mn4 building blocks to develop new SMMs and
SCMs which operate at high temperatures. ?? the Owner Societies. |