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

Abstract

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 n BuMnO4 or MnII salts as initiators. Reactions using MeCO2H in n PrOH or n BuOH gave [Mn70O60(O2CMe)70(O n Pr)20( n PrOH)18.5(H2O)21.5] (3) and [Mn70O60(O2CMe)70(OH)3(O n Bu)17( n BuOH)7.5(H2O)32.5] (4), respectively, whereas EtCO2H in n PrOH gave [Mn84O72(O2CEt)84(O n Pr)24( n PrOH)16(H2O)32] (5). 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-O2– groups and overall are [Mn14]5 and [Mn14]6 oligomers, the repeating unit containing two Mn3 and two Mn4 units. 3/4/5 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″ M signals below ∼2.4 K, indicating 3–5 to be new members of the giant [Mn14] n torus family of giant single-molecule magnets (SMMs), in which Mn84 and Mn70 are the largest homometallic Mn/O clusters and SMMs to date.

Spatiotemporal Studies of Soluble Inorganic Nanostructures with X‐rays and Neutrons

“…To better describe the structures of {Mo 154 } and its derivatives, Yin developed a custom carved ellipsoid model and the scattering function was systematically derived (Figure 2b). [44] This work provided a new geometric model for the scattering community and facilitates the structural studies of other toroidal clusters including [P 8 W 48 O 184 ] 43À , [45] M IV 70 rings (M = U, Ce, Zr), [46] Mn-oxo rings, [47] and palladate rings. [48] In some cases, structural information of MOCs can be read directly from the scattering curves without complex model fitting.…”

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

“…[17] In addition to their classical characteristics, SMMs can also exhibit quantum properties such as quantum tunneling of magnetization (QTM) [18,19] and quantum phase interference, and they have thus been proposed for a variety of potential technological applications, including molecular spintronics and quantum computation. [20][21][22] We, and others, have had a continuing interest in the development of new synthetic strategies for the isolation of Mn clusters possessing high nuclearities, [23][24][25] novel structural characteristics [26][27][28] and interesting magnetic properties. [29][30][31] To this end, various organic chelating/bridging ligands with diverse functionalities have been utilized, such as (poly)alcohols [32][33][34][35] or oximates.…”

Rare Nuclearities and Unprecedented Structural Motifs in Manganese Cluster Chemistry from the Combined Use of Di-2-Pyridyl Ketone with Selected Diols

“…The synthesis of several Mn SMMs, including the first one [Mn 12 O 12 (OAc) 16 (H 2 O) 4 ] [33,34], triggered interest in this area, and led to several new clusters and many synthetic strategies. As a result, Mn clusters with enhanced magnetic properties and impressive crystal structures have been reported, including the giant [Mn 84 ] [35,36] and [Mn 70 ] [36,37] torus-like complexes, which are the highest nuclearity 3d SMMs, and the [Mn 49 ] aggregate [38], possessing a highly symmetric cuboctahedral core. These results demonstrate the special role of manganese in nanoscience and molecular magnetism, and to some extent explain why synthetic efforts are still focusing on the isolation of new Mn clusters.…”