Search

We report two solvothermal pathways toward intercalated iron sulfide, [Fe8S10]Fe(en)3·en0.5 (en = ethylenediamine), featuring [Fe8S10]2– layers stacked by [Fe(en)3]2+ cations and free ethylenediami...

A one-dimensional (1D) chain compound [Fe(en)3]3(FeSe2)4Cl2 (en = ethylenediamine), featuring tetrahedral FeSe2 chains separated by [Fe(en)3]2+ cations and Cl– anions, has been synthesized by a low...

A one-dimensional (1D) chain compound

An isostructural series of transition metal-formate-chloride-hydrate compounds, M3(OOCH)5Cl(OH2) (M = Fe, Co, Ni), have been synthesized using a solvothermal method. These compounds crystallize in the chiral and polar space group P31 and are comprised of three different types of helical chains of edge-sharing M2+-centered octahedra. All three compounds undergo 3D ferrimagnetic ordering at low temperature, and the iron and cobalt analogues exhibit field-induced metamagnetic transitions. The magnetic structure was determined by neutron powder diffraction, revealing ferromagnetic intrachain coupling and antiferromagnetic interchain interactions, with the three chains arranged in a two-up/one-down triangular lattice. As all three chains contain one type of metal in the same spin state, these compounds are rare examples of homospin topological ferrimagnets.

Four new quaternary pnictides, R2Mg3SiPn6 (R = La, Ce; Pn = P, As), were synthesized via high-temperature solid-state reactions and gas-phase transport reactions with iodine. Their crystal structures were determined by single crystal X-ray diffraction. All four compounds are isostructural and crystallize in a new structure type in the orthorhombic space group Pnma (No. 62, Z = 4), Pearson symbol oP48. The crystal structures of R2Mg3SiPn6 are composed of two-dimensional puckered MgP3 layers, which are connected in a three-dimensional framework by P–P dimers and MgSiP4 double-tetrahedral chains. Rare-earth cations are encapsulated inside the channels of the framework running along [010]. Quantum-chemical calculations predict that La2Mg3SiP6 is an indirect narrow bandgap semiconductor. The Mg–P bonding in MgP4 tetrahedra and MgP6 octahedra was analyzed by means of crystal orbital Hamilton population (COHP) analysis. Magnetic characterization of Ce-containing compounds confirmed the trivalent nature of cerium...

Conditions for the crystallization and interconversion of the green and brown polymorphs of bis(3-ethylamino-1-phenyl-but-2-en-1-ono)nickel(II) (Ni(B–Et)2), which contain planar and tetrahedral complexes in accord with previous magnetic and spectroscopic studies, have been determined. Additionally, the series of β-diketoamine-containing complexes, M(B–Et)2 and M(B–Bn)2, (M = CoII, NiII, CuII, ZnII) obtained from condensation of benzoylacetone (B) with either ethylamine (Et) or benzylamine (Bn) followed by treatment with [MCl4]2− under basic conditions has been prepared and their structures characterized crystallographically. In contrast to Ni(B–Et)2, Ni(B–Bn)2 has been crystallized only in the planar form. M(B–Et)2 and M(B–Bn)2 (M = Co or Zn) have similar, nearly tetrahedral structures, while Cu(B–Et)2 and Cu(B–Bn)2 have structures that are decidedly intermediate between tetrahedral and planar. Despite the abilities of these complexes to exist in tetrahedral, planar, or intermediate structures in solution, it has not been possible to induce much structural variation in crystalline forms. While two polymorphs of Zn(B–Bn)2 have been obtained, both have similar, tetrahedral structures. Only Ni(B–Et)2 crystallizes in both planar and tetrahedral forms. None of the complexes formed cocrystals with fullerenes or solvates in which structural variation as seen in Ni(B–Et)2 occurred.

Two new barium iron pnictide–selenides, Ba2FeSbSe5 and Ba2FeBiSe5, were synthesized by a high-temperature solid-state route and their crystal structures were determined using single crystal X-ray diffraction. Both compounds are isomorphic to the high pressure phase Ba3FeS5 and crystallize in the orthorhombic space group Pnma (No. 62) with cell parameters of a=12.603(2)/12.619(2) A, b=9.106(1)/9.183(1) A, c=9.145(1)/9.123(1) A and Z=4 for Ba2FeSbSe5 and Ba2FeBiSe5, respectively. According to differential scanning calorimetry, Ba2FePnSe5 compounds exhibit high thermal stability and melt congruently at 1055(5) K (Pn=Sb) and 1105(5) K (Pn=Bi). Magnetic characterizations reveal strong antiferromagnetic nearest-neighbor interactions in both compounds resulting in an antiferromagnetic ordering at 58(1) K for Ba2FeSbSe5 and 79(2) K for Ba2FeBiSe5. The magnetic interactions between Fe3+ centers, which are at least 6 A apart from each other, are mediated by superexchange interactions.

In this paper, an ambient-pressure solution route and an improved solvothermal synthetic method have been developed to produce polycrystalline powders and large single crystals of NH4MCl2(HCOO) (M=Fe, Co, Ni). The magnetic structure of the 1D linear chain compound NH4FeCl2(HCOO) has been determined by low-temperature neutron powder diffraction, revealing ferromagnetic intra-chain interactions and antiferromagnetic inter-chain interactions. Finally, the newly-reported Co and Ni analogs are isostructural with NH4FeCl2(HCOO), but there are significant differences in the magnetic properties of each compound; the Ni analog behaves similarly to the Fe compound but with stronger magnetic coupling, exhibiting antiferromagnetic ordering (TN=8.5 K) and a broad metamagnetic transition between 2 and 5 T, while the Co analog does not order magnetically above 2 K, despite strong antiferromagnetic nearest-neighbor interactions.

A new low-temperature solvothermal synthesis of superconducting β-FeSe has been developed using elemental iron and selenium as starting materials. We have shown that syntheses performed in aerobic conditions resulted in the formation of nonsuperconducting antiferromagnetic β-FeSe, whereas syntheses performed in ultra-dry and oxygen-free conditions produced superconducting β-FeSe. Detailed characterization of both types of samples with magnetometry, resistivity, Mossbauer spectroscopy, synchrotron X-ray and neutron powder diffraction, and pair-distribution function analysis uncovered factors that trigger the loss of superconductivity in β-FeSe. Vacancies in the iron sublattice and the incorporation of disordered oxygen-containing species are typical for nonsuperconducting antiferromagnetic samples, whereas a pristine structure is required to preserve superconductivity. Exposure to ambient atmosphere resulted in the conversion of superconducting samples to antiferromagnetic ones. This synthetic method creat...

The synthesis and structural characterization is reported for [Fe(dien)2][FeSe2]2 and [Fe(tren)][FeSe2]2, two new mixed-valence compounds that contain infinite ∞(1)(FeSe2) tetrahedral chains separated by Fe-amine complexes. The inter- and intra-chain magnetic interactions can be controlled by changing the denticity of the amine while preserving the general structural motif.

Four new quaternary pnictides, R

1,3,5-Tris(4-carboxyphenyl)benzene assembles into an intricate 8-fold polycatenated assembly of (6,3) hexagonal nets formed through hydrogen bonds and π-stacking. One polymorph features 56 independent molecules in the asymmetric unit, the largest Z' reported to date. The framework is permanently porous, with a BET surface area of 1095 m(2) g(-1) and readily adsorbs N2, H2 and CO2.

Shiny black needle-like crystals of Fe3Se4(en)2 are solvothermally synthesized from a mixture of elemental Fe and Se, en, and NH4Cl as a mineralizer (autoclave, 773 K, 5 d).

Solvothermal synthesis was used to create a low-dimensional iron(II) chloride formate compound, NH4FeCl2(HCOO), that exhibits interesting magnetic properties. NH4FeCl2(HCOO) crystallizes in the monoclinic space group C2/c (No. 15) with a = 7.888(1) Å, b = 11.156(2) Å, c = 6.920(2) Å, and β = 108.066(2)°. The crystal structure consists of infinite zigzag chains of distorted Fe(2+)-centered octahedra linked by μ2-Cl and syn-syn formate bridges, with interchain hydrogen bonding through NH4(+) cations holding the chains together. The unique Fe(2+) site is coordinated by four equatorial chlorides at a distance of 2.50 Å and two axial oxygens at a distance of 2.08 Å. Magnetic measurements performed on powder and oriented single-crystal samples show complex anisotropic magnetic behavior dominated by antiferromagnetic interactions (TN = 6 K) with a small ferromagnetic component in the direction of chain propagation. An anisotropic metamagnetic transition was observed in the ordered state at 2 K in an applied magnetic field of 0.85-3 T. (57)Fe Mössbauer spectroscopy reveals mixed hyperfine interactions below the ordering temperature, with strong electric field gradients and complex noncollinear arrangement of the magnetic moments.

Fragments of the superconducting FeSe layer, FeSe2 tetrahedral chains, were stabilized in the crystal structure of a new mixed-valent compound Fe3Se4(en)2 (en = ethylenediamine) synthesized from elemental Fe and Se. The FeSe2 chains are separated from each other by means of Fe(en)2 linkers. Mossbauer spectroscopy and magnetometry reveal strong magnetic interactions within the FeSe2 chains which result in antiferromagnetic ordering below 170 K. According to DFT calculations, anisotropic transport and magnetic properties are expected for Fe3Se4(en)2. This compound offers a unique way to manipulate the properties of the Fe–Se infinite fragments by varying the topology and charge of the Fe-amino linkers.