Mixed‐Valence Manganese Carboxylate Clusters, {MnIII6MnII4}, {MnIII7MnII5Na}, and {MnIII7MnII5}, Derived from the Combined Use of Di‐2‐pyridyl Ketone with Selected Aliphatic Diols

The combined use of di-2-pyridyl ketone with the aliphatic diols 1,3-propanediol (pdH₂) or 1,4-butanediol (1,4-bdH₂) in manganese carboxylate chemistry has afforded three new polynuclear clusters with the {Mn^III ₆Mn^II ₄} and {Mn^III ₇Mn^II ₅} nuclearities. The compounds feature unique multilayer cores, not previously observed in manganese cluster chemistry, and possess interesting magnetic properties.

Abstract

Three new polynuclear clusters with the formulae [Mn₁₀O₄(OH)(OMe){(py)₂C(O)₂}₂{(py)₂C(OMe)(O)}₄(MeCO₂)₆](ClO₄)₂ (1), Na[Mn₁₂O₂(OH)₃(OMe){(py)₂C(O)₂}₆{(py)₂C(OH)(O)}₂(MeCO₂)₂(H₂O)₁₀](ClO₄)₈ (2) and [Mn₁₂O₄(OH)₂{(py)₂C(O)₂}₆{(py)₂C(OMe)(O)}(MeCO₂)₃(NO₃)₃(H₂O)(DMF)₂](NO₃)₂ (3) were prepared from the combination of di-2-pyridyl ketone, (py)₂CO, with the aliphatic diols (1,3-propanediol (pdH₂) or 1,4-butanediol (1,4-bdH₂)) in Mn carboxylate chemistry. The reported compounds do not include the aliphatic diols employed in this reaction scheme; however, their use is essential for the formation of 1–3. The crystal structures of 1–3 are based on multilayer cores which, to our knowledge, are reported for the first time in Mn cluster chemistry. Direct current (dc) magnetic susceptibility studies showed the presence of dominant antiferromagnetic exchange interactions within 1–3. Alternating current (ac) magnetic susceptibility studies revealed the presence of out-of-phase signals below 3.0 K for 2 and 3 indicating the slow relaxation of the magnetization vector, characteristic of single-molecule magnets; the U_eff value of 2 was found to be 23 K and the preexponential factor τ₀ ~7.6×10⁻⁹ s.

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