Synthesis, Physical Properties, Multitemperature Crystal Structure, and 20 K Synchrotron X-ray Charge Density of a Magnetic Metal Organic Framework Structure, Mn₃(C₈O₄H₄)₃(C₅H₁₁ON)₂

Abstract

A new magnetic metal organic framework material has been synthesized, Mn3(C8O4H4)3(C5H11ON)2, 1. Magnetic susceptibility measurements from 2 to 400 K reveal anti-ferromagnetic ordering at approximately 4 K and a total magnetic moment of 6.0 micro(B). The magnetic phase transition is confirmed by heat capacity data (2-300 K). The crystal structure is studied by conventional single-crystal X-ray diffraction data at 300, 275, 250, 225, 200, 175, 150, 125, and 100 K, and synchrotron data at 20 K. There is a phase transition between 100 and 20 K due to ordering of the diethylformamide molecules. The X-ray charge density is determined based on multipole modeling of a second 20 K single-crystal synchrotron radiation data set. The electron distributions around the two unique Mn centers are different, and both have substantial anisotropy. Orbital population analysis reveals large electron donation (1.7 e) to each Mn atom and the maximum possible number of unpaired electrons is 3.2 for both Mn sites. Thus, there is a considerable orbital component to the magnetic moment. Bader topological analysis shows an absence of Mn-Mn bonding, and the magnetic ordering is via super-exchange through the oxygen bridges. Formal electron counting suggests Mn2+ sites, but this is not supported by the Bader atomic charges, Mn1 = +0.11 e, Mn2 = +0.17 e. The topological measures show the dominant metal-ligand interactions to be electrostatic, and a simple exponential correlation is derived between Mn-O bond lengths and the values of nabla2rho at the bond critical points.

Manganese‐Based Metal–Organic Frameworks as Heterogeneous Catalysts for the Cyanosilylation of Acetaldehyde

“…The Mn1-O bond lengths are in agreement with distances reported earlier for similar coordination environments. [18] The coordination angles, ranging from 86.02 (13) to 93.98(13)°( see Table 2), are close to 90°, the ideal value for a perfect octahedron. Mn1 is bridged to Mn2 and to its symmetryrelated counterpart Mn2a [the distance Mn1-Mn2 is 3.6024(10) Å], generating a trinuclear cluster.…”

“…Two of these MOFs (compounds 1 and 3, see below) have been separately reported; [11][12][13] therefore, their structures were not compared to each other. H 2 tpa is well known in the area of MOF chemistry [14] and has been extensively used.…”

“…[12,13] In addition, Mn1 is semi-coordinated by a bridging carboxylato group, with a Mn1-O6 contact distance of 2.552(3) Å. Mn2 exhibits an octahedral coordination geometry defined by six carboxylato oxygen atoms. Four O donors belong to four different µ-O,OЈ-tpa ligands (oxygen atoms O2, O6, O2a and O6a in Figure 5), while the remaining two are from two µ-O,OЈ,OЈ-tpa ligands (oxygen atoms O4b and O4e in Figure 5).…”

Electron Density Studies in Materials Research

“…The literature on ED related to intermolecular interactions and crystal engineering is large, and we will therefore focus on host–guest structures with relation to storage or sensing of molecules. In these materials, especially calculations of the electrostatic potential (EP) and electric field (EF) in void spaces based on the MM are of great interest as in the example of the coordination polymer above, since it directly relates to the inclusion properties.…”

Crystal structure of catena-poly[bis(glycol-1 k2O,O')-(μ2- tetrafluoroterephthalato)zinc(II)], Zn(C8F4O4)(C2H6O2)2

“…The design and synthesis of metal-organic frameworks constructed from transition metal ions and 1,4-benzenedicarboxylic acid (1, ligand have attracted intensive attention in recent years because of their intriguing structural topologies and tailor-made applications as functional solid materials [1][2][3]. Recent studies have shown the remarkable analogy of 1,4-BDC-type ligands with bulky methyl [4], fluorine [5], chlorine [6] or bromine [7] groups, since they not only provide astonishing thermal and chemical stability and stereo-chemical characteristics, but also prevent interpenetration phenomena of resultant polymeric networks.…”