Molecular-Based Magnetism in Bimetallic Two-Dimensional Oxalate-Bridged Networks. An X-ray and Neutron Diffraction Study

Abstract

Bimetallic, oxalate-bridged compounds with bi- and trivalent transition metals comprise a class of layered materials which express a large variety in their molecular-based magnetic behavior. Because of this, the availability of the corresponding single-crystal structural data is essential to the successful interpretation of the experimental magnetic results. We report in this paper the crystal structure and magnetic properties of the ferromagnetic compound {[N(n-C(3)H(7))(4)][Mn(II)Cr(III)(C(2)O(4))(3)]}(n)() (1), the crystal structure of the antiferromagnetic compound {[N(n-C(4)H(9))(4)][Mn(II)Fe(III)(C(2)O(4))(3)]}(n)() (2), and the results of a neutron diffraction study of a polycrystalline sample of the ferromagnetic compound {[P(C(6)D(5))(4)][Mn(II)Cr(III)(C(2)O(4))(3)]}(n)() (3). Crystal data: 1, rhombohedral, R3c, a = 9.363(3) Å, c = 49.207(27) Å, Z = 6; 2, hexagonal, P6(3), a = 9.482(2) Å, c = 17.827(8) Å, Z = 2. The structures consist of anionic, two-dimensional, honeycomb networks formed by the oxalate-bridged metal ions, interleaved by the templating cations. Single-crystal field dependent magnetization measurements as well as elastic neutron scattering experiments on the manganese(II)-chromium(III) samples show the existence of long-range ferromagnetic ordering behavior below T(c) = 6 K. The magnetic structure corresponds to an alignment of the spins perpendicular to the network layers. In contrast, the manganese(II)-iron(III) compound expresses a two-dimensional antiferromagnetic ordering.

Funktionale poröse Koordinationspolymere

“…Das 1D-Strukturmotiv von {Cu(ca)(ROH) 2 } enthält Wasserstoffbrückenstellen, ca-O (H-Acceptor) und ROH (H-Donor), [111] sodass [195,235] Die Verbindungen zeigen ferromagnetisches, [196] ferrimagnetisches [199,236,237] oder gekippt-antiferromagnetisches Verhalten [238,239] mit kritischen Temperaturen zwischen 5 und 44 K. Die Strukturen [197,240] bestehen aus einem kontinuierlichen anionischen Netzwerk von Oxalat-verbrückten hexagonalen Schichten der beiden Metallatome. Zwischen den Schichten befindet sich ein organisches Gegenion des Typs [XR 4 ] + (X = N, P; R = Ph, nPr, nBu), das wahrscheinlich als Templat fungiert und den Aufbau der Netzstruktur beeinflusst.…”

Charge‐Transfer Phase Transition and Ferromagnetism of Iron Mixed‐Valence Complexes (n‐CnH2n+1)4N[FeIIFeIII(dto)3] (n = 3–6; dto = C2O2S2)

“…This structure is common in heterometal oxalato and dithiooxalato complexes. [11,12] The space group of (n-C 3 H 7 ) 4 3 ] (n = 4-6) appear to have honeycomb structures that are restricted to the ab plane. For these crystals, the lattice parameter c increases with the number of carbon atoms in (n-C n H 2n+1 ) 4 N + , a relationship based on results from the analogous complexes (n-C n H 2n+1 ) 4 4 (n = 3-5) and P(C 6 H 5 ) 4 ].…”

Hybrid Magnetic Materials Based on Nitroxide Free Radicals and Extended Oxalato‐Bridged Bimetallic Networks

“…[3Ϫ5] The majority of the resultant structures are composed of edge-sharing octahedra and belong to two categories, namely a) 2D bimetallic compounds of formula A[MЈM(ox) 3 ] (A ϭ quaternary onium cation, MЈ ϭ metal) with a honeycomb-layered structure [6,7] and b) 3D homometallic compounds of formulae A[M 2 Ј (ox) 3 3 ] 2ϩ ) with a cubic chiral packing. [8,9] Since the formation of each structural type depends on the use of a particular A mϩ cation, these have been considered as templating agents for the host structure.…”