Synthetic Factors Determining the Curvature and Nuclearity of the Giant Mn₇₀ and Mn₈₄ Clusters with a Torus Structure of ∼4 nm Diameter

New members of the Mn₇₀ and Mn₈₄ torus-like cluster family have been prepared from a hybrid comproportionation–alcoholysis reaction of [Mn₁₂O₁₂(O₂CR)₁₆(H₂O)₄] in alcohol in the presence of R′CO₂H with N^<i>n</i>BuMnO₄ or Mn^II salts as initiators. Reactions using MeCO₂H in ^<i>n</i>PrOH or ^<i>n</i>BuOH gave [Mn₇₀O₆₀(O₂CMe)₇₀(O^<i>n</i>Pr)₂₀(^<i>n</i>PrOH)_18.5(H₂O)_21.5] (<b>3</b>) and [Mn₇₀O₆₀(O₂CMe)₇₀(OH)₃(O^<i>n</i>Bu)₁₇(^<i>n</i>BuOH)_7.5(H₂O)_32.5] (<b>4</b>), respectively, whereas EtCO₂H in ^<i>n</i>PrOH gave [Mn₈₄O₇₂(O₂CEt)₈₄(O^<i>n</i>Pr)₂₄(^<i>n</i>PrOH)₁₆(H₂O)₃₂] (<b>5</b>). They consist of alternating near-linear [Mn₃(μ₃-O)₄]⁺ and distorted-cubane [Mn₄(μ₃-O)₂(μ₃-OR)₂]⁶⁺ units bridged by syn,syn-μ-RCO₂^– and μ₃-O^2– groups and overall are [Mn₁₄]₅ and [Mn₁₄]₆ oligomers, the repeating unit containing two Mn₃ and two Mn₄ units. <b>3</b>/<b>4</b>/<b>5</b> possess external diameters (including organic ligands) of 4.0/4.1/4.6 nm, respectively, and crystallize as supramolecular nanotubes but with different packing arrangements. Considering all Mn₇₀/Mn₈₄ tori now available, we conclude that the Mn₇₀ vs Mn₈₄ nuclearity is determined by the relative bulk of the carboxylates vs the alkoxides, their increasing bulk favoring Mn₈₄ and Mn₇₀, respectively, with carboxylates larger than acetate giving Mn₈₄. Alternating current (ac) magnetic susceptibility studies revealed frequency-dependent χ<i>″</i>_<i>M</i> signals below ∼2.4 K, indicating <b>3–5</b> to be new members of the giant [Mn₁₄]_<i>n</i> torus family of giant single-molecule magnets (SMMs), in which Mn₈₄ and Mn₇₀ are the largest homometallic Mn/O clusters and SMMs to date.