Synthesis, structure and magnetic properties of organic-intercalated bimetallic molecular-based ferrimagnets (n-CnH2n+1)PPh3MIIFeIII(C2O4)3, (MII = Mn, Fe; n = 3–7)

Abstract

Bimetallic tris-oxalato-salts (n-C n H 2nϩ1 )PPh 3 M II Fe III (C 2 O 4 ) 3 (n = 3-7, M II = Mn, Fe) were prepared and the structures investigated by powder X-ray diffraction in order to study the evolution of the structure and magnetic properties as a function of alkyl chain length. The compounds all have the same two-dimensional honeycomb structure of M II and Fe III bridged by oxalate, with the organic cations lying between the metal-oxalate layers, whose separation ranges from 9.48 Å (n = 3) to 11.10 Å (n = 7) for the Fe II salts and 9.37 to 10.81 Å for Mn II . The compounds all behave as ferrimagnets, with magnetic parameters similar to the corresponding AM II Fe III (C 2 O 4 ) 3 with A = NR 4 ϩ , PPh 4 ϩ and T c s almost insensitive to interlayer separation. The Mn II salts exhibit uncompensated magnetisation below T c and the Fe II ones show Néel type N ferrimagnetism, with negative magnetisation at low temperature, the magnitude of which is influenced by the preparation conditions, due to vacancies in the Fe II sublattice.

Calorimetric investigation of phase transitions in the layered antiferromagnetic molecule-based material {N(n-C5H11)4[MnIIFeIII(ox)3]}∞(ox=oxalato)

“…At this point, one may recall that spin canting was expected from the magnetic measurement of {N(n-C 5 H 11 ) 4 [Mn II Fe III (ox) 3 ]} N [4]. Below T N , this and analogous materials exhibited a jump in the magnetization arising probably from the uncompensated magnetic moment [4,6]. Vissar et al [11] assumed the similar uncompensated magnetization observed in {P(C 6 D 5 ) 4 [Mn IIFe III (ox) 3 ]} N as the manifestation of weak ferromagnetic alignment of Mn II and Fe III spins at low temperatures.…”

“…The magnetic property of this material system may mimic that of a two-dimensional classical antiferromagnet [16]. This system {A[Mn II Fe III (ox) 3 ]} N has received much attention recently [4,6,11,13,17]. Compounds with different organic cations with the same Mn II -ox-Fe III layer have been studied magnetically.…”

“…One such class of molecule-based magnets is {A[M II M III (ox) 3 ]} N , (A: organic cation, M II , M III : transition metal ions, ox: oxalato ligand). The variability of the cation A and the M II -ox-M III has led to a broad array of materials exhibiting different magnetic phenomena [2][3][4][5][6]. Crystal structure determination of these materials has revealed that these are crystallized in quasi-2D and 3D honeycomb M II -ox-M III networks [7,8].…”

Synthesis, structure and magnetic behavior of new 1D metal–organic coordination polymer with Fe3O core

“…In particular, new mixed valence iron(II) formate, (Me 2 NH 2 )[Fe 2 (HCOO) 6 ], was recently described [8]. This compound has 3D polymeric framework and demonstrates spontaneous magnetization at low temperatures followed by negative magnetization, a very rarely observed phenomenon [9][10][11][12][13]. Well-known iron carboxylates with Fe 3 O core are another example where interesting magnetic properties may render through interactions over short formate bridging ligands [14][15][16].…”

Synthesis, crystal structure and magnetic characterization of Na2Cu5(Si2O7)2: An inorganic ferrimagnetic chain

“…The hydrothermal approach is one of such methods that operate far from thermodynamical equilibrium. Materials with a magnetic one-dimensional character, just as their three-dimensional counterparts, may exhibit ferro, [6] antiferro, [7] and ferrimagnetic ordering [8]. In general, the latter is achieved by incorporating two magnetic cations, with different S (be that different species or just different oxidation states) that couple antiferromagnetically, resulting in uncompensated spins.…”