A Mn36Ni4 ‘loop-of-loops-and-supertetrahedra’ aggregate possessing a high ST = 26 ± 1 spin ground state

Abstract

The initial use of 1,3-propanediol in mixed Mn/3d cluster chemistry has led to a Mn(III)(28)Mn(II)(8)Ni(II)(4) molecular aggregate which consists of two Mn(III)(8)Ni(2) loops and two Mn(III)(6)Mn(II)(4) supertetrahedral units and displays a high ground spin state value S(T) = 26 ± 1.

Magnetic “Molecular Oligomers” Based on Decametallic Supertetrahedra: A Giant Mn49 Cuboctahedron and its Mn25Na4 Fragment

“…The construction of giant metal clusters based on tightly connected, magnetically interesting, polynuclear complexes is one of the most important challenges for coordination chemists.I nterest in such compounds stems not only from their impressive structural features,s uch as large size,h igh symmetry,b eautiful shapes,a nd architectures,b ut also from the possibility that the magnetic properties of their structural subunits can be retained or even enhanced in the large polynuclear assembly.A lthough several giant metal-organic compounds have been reported, the structures of both the homometallic (for example,M n 84 , [1] Mn 44 , [2] Mn 32 , [3][4][5] Fe 64 , [6] Fe 42, [7] Co 36, [8] Cu 44 , [9] Pd 84 , [10] and Ln 104 (Ln = Nd, Gd) [11] )a nd heterometallic (for example,M n 36 Ni 4 , [12] Cu 17 Mn 28 , [13] [Ni 12 -(Cr 7 Ni) 6 ], [14] Ni 60 La 76 , [15] Ni 54 Gd 54 , [16] Cu 36 Ln 24 (Ln = Gd, Dy) [17] )c omplexes contain mainly oligonuclear, usually trinuclear (such as oxo or hydroxo-centered triangles) and tetranuclear (such as cubanes) subunits.T here are also afew examples of nanosized clusters based on subunits that have not been isolated in ad iscrete form and only ac ouple of complexes displaying building units or fragments that have been reported in the literature.S uch examples are the Fe 64 cluster based on an Fe 8 subunit [6] and the Mn 84 wheel which contains aM n 11 fragment reported in the past, although its true repeating unit is aM n 14 cluster never seen in discrete form. [1] Although the synthesis of most giant metal-organic clusters is avery complicated process based to some extent on serendipity,adiscussion has been initiated in the literature concerning the possibility to predict the structure and nuclearity of metal-organic clusters that could be targeted and prepared by future generations of chemists.…”

“…One ideal structural type to act as abuilding block in high nuclearity clusters is the [Mn III 6 Mn II 4 (m 4 -O) 4 ] 18+ supertetrahedral core which combines ab eautiful, high symmetry (T d ) metal topology and interesting magnetic properties. [19] In addition, it has been stabilized in discrete form with several ligands [19][20][21] and under various reaction conditions,a nd has appeared as the repeating unit in zero-dimensional Mn 17 [22,23] and Mn 19 [24] clusters and in the giant Mn 36 Ni 4 "loop-of-loops and supertetrahedra" aggregate, [12] , with that of 1 describing an "A rchimedean solid" called ac uboctahedron. Additionally,t he compounds are structurally related, with the core of 2 being almost identical to afragment of that of 1.Magnetism studies revealed the existence of dominant ferromagnetic exchange interactions in both 1 and 2 leading to ground-state spin values of 61/2 and 51/2, respectively.I na ddition, the magnetocaloric effect for both complexes is seen to develop over as ignificantly wide temperature range.F inally,c ompound 1 displays single-molecule magnet (SMM) behavior and is the second largest homometallic 3d SMM reported to date.…”

Recent Progress in the Realm of Homonuclear Ln6 Single molecule magnets: Structural Overview and Synthetic Approaches

“…Typically, the first category is represented by symmetric arrangement of the six metal centers to construct a metallic wheel/ring, while the other category is typified by the relatively more familiar combinations of interconnected triangles. Rather than distinguishing these SMM materials based on the symmetry-aspect, it seems more judicious to divide the entire regime of the reported hexanuclear SMMs into two more general broad classifications: First class being the homonuclear Ln 6 series where the metal centers are solely 4f-elements, whereas the second class comprises of the heteronuclear entities composed of both 3d-and 4f-metal centers (Randell et al, 2013;Boskovic et al, 2002;Brechin et al, 2002;King et al, 2004;Zheng et al, 2007;Manoli et al, 2007;Feng et al, 2010;Stamatatos et al, 2011;Nayak et al, 2010;Kotzabasaki et al, 2011;Yang et al, 2011;Costa et al, 2012;Charalambous et al, 2012;Chakraborty et al, 2012;Mukherjee et al, 2014). Hereafter, our discussion will revolve around the first class only.…”

Magnetic “Molecular Oligomers” Based on Decametallic Supertetrahedra: A Giant Mn49 Cuboctahedron and its Mn25Na4 Fragment

“…Interest in such compounds stems not only from their impressive structural features, such as large size, high symmetry, beautiful shapes, and architectures, but also from the possibility that the magnetic properties of their structural subunits can be retained or even enhanced in the large polynuclear assembly. Although several giant metal–organic compounds have been reported, the structures of both the homometallic (for example, Mn 84 ,1 Mn 44 ,2 Mn 32 ,3–5 Fe 64 ,6 Fe 42, 7 Co 36, 8 Cu 44 ,9 Pd 84 ,10 and Ln 104 (Ln=Nd, Gd)11) and heterometallic (for example, Mn 36 Ni 4 ,12 Cu 17 Mn 28 ,13 [Ni 12 (Cr 7 Ni) 6 ],14 Ni 60 La 76 ,15 Ni 54 Gd 54 ,16 Cu 36 Ln 24 (Ln=Gd, Dy)17) complexes contain mainly oligonuclear, usually trinuclear (such as oxo or hydroxo‐centered triangles) and tetranuclear (such as cubanes) subunits. There are also a few examples of nanosized clusters based on subunits that have not been isolated in a discrete form and only a couple of complexes displaying building units or fragments that have been reported in the literature.…”

“…One ideal structural type to act as a building block in high nuclearity clusters is the [Mn III 6 Mn II 4 (μ 4 ‐O) 4 ] 18+ supertetrahedral core which combines a beautiful, high symmetry ( T d ) metal topology and interesting magnetic properties 19. In addition, it has been stabilized in discrete form with several ligands19–21 and under various reaction conditions, and has appeared as the repeating unit in zero‐dimensional Mn 17 22, 23 and Mn 19 24 clusters and in the giant Mn 36 Ni 4 “loop‐of‐loops and supertetrahedra” aggregate,12 all containing two Mn III 6 Mn II 4 supertetrahedral units. Most of the compounds possessing this core display ferromagnetic exchange interactions and large or even giant ground‐state spin values, which for the Mn 10, Mn 17 , Mn 19 , and Mn 36 Ni 4 clusters mentioned above are S =22, 37, 83/2, and 26, respectively.…”