Diverse Family of Layered Frustrated Magnets with Tailorable Interlayer Interactions

Abstract

Single crystals of the compounds I, II and III were synthesised by hydrothermal methods using 23 mL teflonlined autoclaves. Starting materials from commercial companies were applied without further processing. For I, FeC2O42H2O, oxalic acid, KBF4 and K2CO3 were sealed within the autoclave with 2 mL distilled water in a molar ratio of 1:3:2:4. Reactions were performed at 160-190 °C for two days. For II, FeC2O42H2O, oxalic acid, sulfuric acid and Na2CO3 were reacted with 0.5 mL distilled water in a molar ratio of 10:15:10:2. Reactions were performed at 190 °C for four days. For III, FeCl22H2O, oxalic acid, and Li2CO3 were reacted with 5 mL 1M acetic acid in a molar ratio of 1:1:3. The autoclave was kept at 120°C for four days. After heating, the autoclaves were cooled down in air. The resulting products were repeatedly washed with distilled water and acetone and dried at 60°C. Similar procedures were carried out with variants of reactant ratios, water, temperature and time. Unsuccessful reactions typically produced yellow FeC2O42H2O crystallites. Single crystal X-ray diffraction. Transparent crystallites were selected and mounted on nylon loops in inert oil and SXRD data were collected on a Rigaku SCX Mini diffractometer using Mo Kα radiation (λ = 0.710 73 Å) at 173 K. Rigaku CrystalClear 2.0 was employed to index and process the data. Structures were then solved by direct methods and refined using SHELX-2014 1 incorporated in the WinGX program. Absorption corrections were performed semi-empirically from equivalent reflections on the basis of multi-scans. Non-H atoms were refined anisotropically. Characterisation: Fourier-transform infrared spectroscopy was carried out with the objective of determining the coordination of atoms in the sample and to detect any incorporation of H2O or OH-. The mid-infrared spectrum was obtained at room temperature using a Perkin Elmer Spectrum GX IR spectrometer. The spectra were collected in the range 400 to 4000 cm-1 with a resolution of 1 cm-1. Powder X-ray diffraction PXRD patterns were recorded on a Stoe STADI/P diffractometer operating in transmission mode with Fe Kα1 radiation (λ = 1.936 Å) in the 2θ range 10 °-100 °. Step scan mode, step size 0.4 °, steps time 250 s. Data sets were refined by conventional Rietveld methods using the GSAS package with the EXPGUI interface. 2 The refinement of the orthorhombic Cmc21 structural model of KFe(C2O4)F to room temperature PXRD data yields lattice constants a = 7.7802(1) Å, b = 11.8831(2) Å and c = 10.4216(2)Å. The background, scale factor, zero point, lattice parameters and coefficients for the peak shape function were refined to convergence. Thermogravimetric analysis (TGA) were carried out with hand-ground crystals using NETZSCH TG 209 thermal analyser. Samples (about 5 mg) of ground crystallites were placed in an alumina crucible and heated from room temperature until no obvious weight loss at a rate of 5 o C /min in flowing air atmosphere. The residues were examined and analysed by PXRD, all of which showed a typical pattern o...

Hybrid Inorganic‐Organic Frameworks: Synthesis and Crystal Structures of RbFe(SO4)(C2O4)0.5·H2O and CsM(SO4)(C2O4)0.5·H2O (M = Mn, Fe)

“…Observed bands at 1650 and 1383 cm –1 in RbFe(SO 4 )(C 2 O 4 ) 0.5 · H 2 O, at 1624 and 1399 cm –1 in CsMn(SO 4 )(C 2 O 4 ) 0.5 · H 2 O and at 1651 and 1380 cm –1 in CsFe(SO 4 )(C 2 O 4 ) 0.5 · H 2 O are due to ν(CO) stretching, which are comparable to those in K 2 Ni(C 2 O 4 ) 2 · 6H 2 O and K 6 [Mo 6 V 2 O 24 (C 2 O 4 ) 2 ] · 6H 2 O . Bands at 806, 802, and 804 cm –1 can be assigned to O–C=O bending modes, which are consistent with those of Co[Ni(C 2 O 4 ) 2 ] · 5H 2 O and Na 2 Fe(C 2 O 4 )(SO 4 ) · H 2 O …”

“…A careful inspection of the literature shows that 2D [Fe(C 2 O 4 )] ∞ layers are characteristic for several hydrothermally prepared oxalates , . It can show a distinct interlayer bridging mode, a single ion (F – ) bridge in KFe(C 2 O 4 )F, an anion SO 4 2– bridge in Na 2 Fe(C 2 O 4 )(SO 4 ) · H 2 O and an anion C 2 O 4 2– bridge in K 4 Na 2 [Fe(C 2 O 4 ) 2 ] 3 · 2H 2 O . [FeO 6 ] octahedra are connected by C 2 O 4 2– anions to form two‐dimensional [Fe(C 2 O 4 )] ∞ layers, F – ions, SO 4 2– tetrahedra, and C 2 O 4 2– anions link adjacent two‐dimensional [Fe(C 2 O 4 )] ∞ layers to construct a three‐dimensional framework for these three compounds.…”

“…Moreover homeleptic and heteroleptic oxalate complexes have been reported as well as complexes with two or more coordinated metal ions, giving rise to a plethora of compounds. Some examples are Na 2 Fe(C 2 O 4 )F 2 , Na 2 Cu(C 2 O 4 ) 2 , Na 2 Cu 2+ (C 2 O 4 ) · 2H 2 O, K 3 [V(C 2 O 4 ) 2 (μ‐SO 4 )] · 2H 2 O, Na 2 Fe 2 (C 2 O 4 ) 3 · 2H 2 O, K 4 Na 2 [Fe(C 2 O 4 ) 2 ] 3 · 3H 2 O, K 2 [Fe(C 2 O 4 )(HPO 4 )(OH 2 )] · H 2 O, Fe 4 (PO 4 )(C 2 O 4 )(H 2 O) 2 , Mn 4 (PO 4 )(C 2 O 4 )(H 2 O) 2 , KFe(C 2 O 4 )F, Li 2 [Fe(C 2 O 4 )Cl 2 ][Fe(C 2 O 4 )(H 2 O) 2 ] · 2H 2 O, and Na 2 Fe(C 2 O 4 )(SO 4 ) · H 2 O . The structures of K 4 Na 2 [Fe(C 2 O 4 ) 2 ] 3 · 3H 2 O, Fe 4 (PO 4 )(C 2 O 4 )(H 2 O) 2 , Mn 4 (PO 4 )(C 2 O 4 )(H 2 O) 2 , KFe(C 2 O 4 )F, and Na 2 Fe(C 2 O 4 )(SO 4 ) · H 2 O are three‐dimensional frameworks.…”

“…To date oxalate sulfate coordination compound Na 2 Fe(C 2 O 4 )(SO 4 ) · H 2 O was found, which crystallizes with a three‐dimensional framework structure consisting of a [Fe(C 2 O 4 )(SO 4 ) · H 2 O] 2– framework and Na + cations in the voids. Herein, we report the synthesis and crystal structures of the three new alkali transition metal sulfate‐oxalates RbFe(SO 4 )(C 2 O 4 ) 0.5 · H 2 O, CsMn(SO 4 )(C 2 O 4 ) 0.5 · H 2 O, and CsFe(SO 4 )(C 2 O 4 ) 0.5 · H 2 O.…”

A Low‐Cost and Environmentally Friendly Mixed Polyanionic Cathode for Sodium‐Ion Storage

“…Herein, we report a known magnetic material, Na 2 Fe(C 2 O 4 )SO 4 ⋅H 2 O, as a potential low‐cost and environmentally friendly NIBs cathode for the first time. The choice of oxalate lies in the fact that the oxalic acid is a relatively strong acid, with acidity (pKα=1.25/4.14) between those of H 2 SO 4 (pKα=−3/1.99) and H 3 PO 4 (pKα=2.15/7.20/12.32).…”