Tailoring magnetic properties in Mn4 molecules: A way to develop single-molecule magnets
Distorted cubane Mn4+Mn3+ 3 single-molecule magnets (SMMs) having the
general chemical formula Mn4+Mn 3+ 3(3-L2-)3( 3-X-)(OAc)- 3(dbm)- 3 (L
O; X various; dbmH dibenzoyl-methane), have been studied using
first-principles calculations. It was shown in our previous paper that
the ferrimagnetic structure of Mn4+Mn3+ 3 SMMs is dominated by the type
hybridization between the dz2 orbitals at the three high-spin Mn3+ ions
and the t2g orbitals at the Mn4+ ion. This result allows us to predict
that the ferrimagnetic structure of Mn4+Mn3+ 3 molecules will be the
most stable with the Mn4+-(3-L2-)-Mn 3+ angle ≈ 90, while synthesized
Mn4+Mn 3+ 3 molecules have ≈ 95. To design new Mn 4+Mn3+ 3 molecules
having a much more stable ferrimagnetic state, one following approach is
suggested: Controlling the Mn4+-(3-L2-)-Mn3+ exchange pathways by
rational variations in ligands to strengthen the hybridization between
Mn ions. By employed N-based ligands to form the Mn4+-(μ3- L2-)-Mn3+
exchange pathways, new distorted cubane Mn 4+Mn3+ 3 molecules with α ≈
90 have been designed. These molecules have the Mn4+-Mn3+ exchange
coupling of about 2.5 times stronger than that of the synthesized Mn
4+Mn3+ 3 molecules. These results should facilitate the rational
synthesis of new SMMs
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