X-ray diffraction and vibrational data for a series of triphosphates type MIINa3P3O10.12H2O (MII = Cu,Ni and Mg) and their anhydrous forms MIINa3P3O10

Chemical preparation methods, X-ray diffraction and vibrational data are reported for six triphosphates type M^IINa₃P₃O₁₀.12H₂O (M^II = Cu, Ni and Mg) and their anhydrous forms M^IINa₃P₃O₁₀. These condensed phosphates are respectively, CuNa₃P₃O₁₀.12H₂O, MgNa₃P₃O₁₀.12H₂O, NiNa₃P₃O₁₀.12H₂O, CuNa₃P₃O₁₀, NiNa₃P₃O₁₀ and MgNa₃P₃O₁₀. The hydrate triphosphates were prepared by the method of ion-exchange resin, where as their anhydrous forms were prepared by total thermal dehydration of M^IINa₃P₃O₁₀.12H₂O (M^II = Cu, Ni and Mg).CuNa₃P₃O₁₀.12H₂O, MgNa₃P₃O₁₀.12H₂O and NiNa₃P₃O₁₀.12H₂O are isotypic, and crystallize in the monoclinic system, space group is P2₁/n, Z = 4, the unit-cell parameters are: CuNa3P3O10.12H2O, a = 15.052(8) Å, b = 9.234(3) Å,c = 14.767(8) Å and β = 90.03(5)°. MgNa3P3O10.12H2O: a = 15.049(1) (1) Å, b = 9.245(4) Å, c = 14 0.722(3) (2) Å and β = 90.00(5)°.NiNa₃P₃O₁₀.12H₂O: a = 15.010(1) Å, b = 9.208(4) Å, c = 14.710(2) Å and β = 90.00(5)°.The anhydrous forms CuNa₃P₃O₁₀, MgNa₃P₃O₁₀ and NiNa₃P₃O₁₀ crystallize in the monoclinic system, space group is P2₁/n, Z = 4, the unit-cell parameters are: CuNa₃P₃O₁₀, a = 12.464(0) Å, b = 8.437(7) Å, c = 12.083(1) Å and β = 109.77(8) °; MgNa₃P₃O₁₀: a = 11.931(4) (1) Å, b = 12.912(2) Å, c = 10.057(0) Å and β = 113.83(2)° and NiNa₃P₃O₁₀: a = 12.686(8)Å, b = 9.271(2) (4) Å, c = 11.440(3) Å and β = 102,95(5)°.     

Structure,infrared and Raman spectroscopic studies of newly synthetic AII(SbV0.50FeIII0.50)(PO4)2 (ABa,Sr, Pb) phosphates with yavapaiite structure

The synthesis and structural study of three new A^II(Sb^V_0.5Fe^III_0.5)(PO₄)₂ (ABa, Sr, Pb) phosphates belonging to the ASbFePO system were reported here for the first time. Structures of [Ba], [Sr] and [Pb] compounds, obtained by solid state reaction in air atmosphere, were determined at room temperature from X-ray powder diffraction using the Rietveld method. Ba^II(Sb^V_0.5Fe^III_0.5)(PO₄)₂ features the yavapaiite-type structure, with space group C2/m, Z = 2 and a = 8.1568(4) Å; b = 5.1996(3) Å c = 7.8290(4) Å; β = 94.53(1)°. A^II(Sb^V_0.5Fe^III_0.5)(PO₄)₂ (ASr, Pb) compounds have a distorted yavapaiite structure with space group C2/c, Z = 4 and a = 16.5215(2) Å; b = 5.1891(1) Å c = 8.0489(1) Å; β = 115.70(1)° for [Sr]; a = 16.6925(2) Å; b = 5.1832(1) Å c = 8.1215(1) Å; β = 115.03(1)° for [Pb]. Raman and Infrared spectroscopic study was used to obtain further structural information about the nature of bonding in selected compositions.     

Preparation of niobium based oxynitride nanosheets by exfoliation of Ruddlesden-Popper phase precursor

A new oxynitride Ruddlesden-Popper phase K_1.6Ca₂Nb₃O_9.4N_0.6.1.1H₂O was synthesized by the topochemical ammonolysis reaction at 700 °C from the oxide Dion-Jacobson phase KCa₂Nb₃O₁₀ in the presence of K₂CO₃. The oxynitride showed good stability with a little loss of nitrogen, even after a few months of exposure to air. Its crystal structure was solved by Rietveld refinement of X-ray powder diffraction data in space group P4/mmm and considering a two-phase mixture, due to the difference in the degree of hydration, with a = 3.894(2) Å and c = 17.90(8) Å for the most hydrated phase and a = 3.927(6) Å and c = 17.09(2) Å for the less one. Optical band gaps were measured by diffuse reflectance in the UV-Visible range indicating a red shift of Eg to the visible region. The oxynitride layered perovskite was then protonated and exfoliated into nanosheets. TEM images and SAED patterns of the nanosheets proved that exfoliation was successful, showing lattice parameters quite compatible with the Rietveld refinement.     

Hydrothermal synthesis,crystal structure and photoluminescent properties of 2D layered zinc phosphate intercalated with 4,4ˈbiphenyl dicarboxylic acid (ZnPO-BDA)

Herein, we report a new inorganic-organic hybrid, (H₃tren)₂?[Zn₃(PO₄)₄(BDA)]?xH₂O (ZnPO-BDA) prepared under hydrothermal conditions. This hybrid structure of zinc phosphate layers pillared with 4,4′-biphenyl-dicarboxylic acid (BDA) was characterized by single-crystal X-ray diffraction. The compound, ZnPO-BDA, crystallizes in the monoclinic crystal system (space group C2) with a = 14.9348(3) Å, b = 8.7058(2) Å, c = 17.6455(5) Å, β = 111.6760(10), V = 2132.02(9) ų, Z = 2. The crystalline host of the 2D zinc phosphate framework was built with vertex linked ZnO₄ and PO₄ tetrahedra and anchored with tris(2-aminoethyl)amine (H₃tren). Biphenyl dicarboxylic acid (BDA) molecules stack between the phosphate framework layers by means of strong hydrogen bonding, resulting in an interlayer distance of 16.4 Å. ZnPO-BDA displayed blue photoluminescence with an emission maximum at 404 nm on photoexcitation at 340 nm.     

Deposition and dielectric characterization of strontium and tantalum-based oxide and oxynitride perovskite thin films

We have synthesized the composition x = 0.01 of the (Sr_1-xLa_x)₂(Ta_1-xTi_x)₂O₇ solid solution, mixing the ferroelectric perovskite phases Sr₂Ta₂O₇ and La₂Ti₂O₇. Related oxide and oxynitride materials have been produced as thin films by magnetron radio frequency sputtering. Reactive sputter deposition was conducted at 750 °C under a 75 vol.% (Ar) + 25 vol.% (N₂,O₂) mixture. An oxygen-free plasma leads to the deposition of an oxynitride film (Sr_0.99La_0.01) (Ta_0.99Ti_0.01)O₂N, characterized by a band gap E_g = 2.30 eV and a preferential (001) epitaxial growth on (001) SrTiO₃ substrate. Its dielectric constant and loss tangent are respectively Epsilon' = 60 (at 1 kHz) and tanDelta = 62.5 × 10⁻³. In oxygen-rich conditions (vol.%N₂ ≤ 15%), (110) epitaxial (Sr_0.99La_0.01)₂(Ta_0.99Ti_0.01)₂O₇ oxides films are deposited, associated to a larger band gap value (E_g = 4.55 eV). The oxide films permittivity varies from 45 to 25 (at 1 kHz) in correlation with the decrease in crystalline orientation; measured losses are lower than 5.10⁻³. For 20 ≤ vol.% N₂ ≤ 24.55, the films are poorly crystallized, leading to very low permittivities (minimum Epsilon' = 3). A correlation between the dielectric losses and the presence of an oxynitride phase in the samples is highlighted.     

A novel mixed-metal borate with large [B12O18(OH)6]6- motif: Synthesis,structure and property

A new mixed-metal polyborate, Na₅Li[B₁₂O₁₈(OH)₆]·2H₂O (1), has been synthesized using solvothermal method and characterized by IR spectroscopy, thermogravimetric analysis, UV–Vis spectroscopy, powder and single-crystal X-ray diffraction, respectively. It crystallizes in the trigonal space group R-3c (No. 167) with unit cell parameters of a = b = 9.6767(6) Å, c = 36.358(5) Å, and Z = 6. Its structure features unprecedented 3D framework constructed from novel honeycomb-shaped inorganic Na-O sheets with unique 12-MR sodium rings and supramolecular polyborate 2D layers of lithium-centered [B₁₂O₁₈(OH)₆]^6-. UV–Vis spectral characterization indicates that compound 1 is a wide-band-gap semiconductor.     

X‐ray crystal of diprotonated tetra‐(2‐pyridyl)pyrazine (H2TPPZ), aqua Fe3+‐phen crystal and new lanthanide complexes of TPPZ and their biochemical studies

New complexes derived from M³⁺ salts with polyazine as monometallic such as [Fe (TPPZ)Cl₃].½H₂O (1) , [Cr (TPPZ)₂Cl₂]Cl.2EtOH (2) , [La (TPPZ)(NO₃)₂(H₂O)₂]NO₃.H₂O (3) in addition to [Fe (Phen)₃]3Cl.7H₂O (4) were isolated. Three bimetallic, [H₂TPPZ][(AuCl₄)₂]. H₂O (5) , [Ce₂(TPPZ)EtOH (NO₃)₃]3NO₃ (6) and [Nd₂TPPZCl₂(H₂O)₄]4Cl.CHCl₃. 4H₂O (7) and mixed ligand complexes, [Fe (TPPZ)(Phen)₂]Cl₃ (8) , [Fe (TPPZ) (Phen)₂][TPPZCl₃] (9) , [La₂(TPPZ)(Phen)₂(EtOH)₂]6Cl.CHCl₃.EtOH.H₂O (10) and [Nd₂(TPPZ)(Phen)Cl₄]2Cl.3H₂O (11) were synthesized and characterized. Crystal data of (4) is tetragonal, I4₁/a, a = b 35.951 (3) Å, c = 11.9055 (8) Å, α = 80.201 (2)° β = 78.846 (2)°, γ = 89.687 (2)° V = 741.06 (5)ų, Z = 1 while triclinic, P1, a = 7.3913 (3) Å, b = 9.7344 (4) Å, c = 10.6577 (4) Å, α = β = γ = 90°, V = 741.06 (5)ų and Z = 170 for (5) . Analyses, spectral and cyclic voltammetry studies indicate the bonding and the redox properties. Anticancer studies promised to be effective in lanthanides and some complexes were screened against antibacterial or antifungal.     

Antimicrobial Investigation and Structural Study of 4′‐Methylazobenzene‐2‐sulfenyl Thiocyanate by X‐Ray Diffraction,DFT, and Ab Initio HF Calculations

4′‐Methylazobenzene‐2‐sulfenyl thio‐cyanate (MABS‐SCN) was synthesized in an aqueous medium and characterized by ¹H nuclear magnetic resonance, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and elemental analysis. The crystal structure was confirmed by single crystal X‐ray diffraction and its geometry was optimized in ground state by Hartree–Fock model and (B3LYP) density functional theory, and in solution (ethanol) using polarized continuum model at restricted HF using the basis set 6–31+G*. The compound crystallizes in orthorhombic space group Pbca, with unit cell parameters a = 7.165 (7) Å, b = 18.846 (2) Å, c = 20.379 (2) Å, V = 2752.1 (5) ų, and Z = 8. It attains a planar thiadiazolium salt structure due to strong ortho azo–sulfur interaction imparting exceptional thermal stability, nonreactive solubility in aqueous medium, and high melting crystalline solid nature. A weak intramolecular C H…S type interaction, one C H…S type, four C H…N type intermolecular hydrogen bonds, and van der Waal's interactions are believed to be the stabilizing force for the crystal structure. MABS‐SCN was also tested for antimicrobial activity.     

Synthesis,X-ray and optical characterizations of two new oxysulfides: LaInS2O and La5In3S9O3

Two new compounds, LaInS₂O and La₅In₃S₉O₃ were synthesized in the La–In–S–O quaternary system. Both compounds crystallize in the orthorhombic system with lattice constants a=20.5421(6) Å, b=14.8490(4) Å, c=3.9829(1) Å for LaInS₂O, and a=4.1018(1) Å, b=26.833(1) Å, c=16.023(1) Å for La₅In₃S₉O₃. The structure of La₅In₃S₉O₃ was solved from single-crystal X-ray data, in the space group Pbcm, with Z=4; it is built from three-atom-thick (100)_NaCl layers interleaved with fluorite-type ribbons, and is closely related to the structures of the known lanthanum and indium compounds La₁₀In₆S₁₇O₆ and La₄In₅S₁₃. Both compounds LaInS₂O and La₅In₃S₉O₃ exhibit a yellow color; measurement of their optical gaps gave 2.73 and 2.60 eV, respectively.     

Synthesis,structure, physical properties,and electronic structure of KGaSe2

The ternary gallium selenide KGaSe₂ has been synthesized by solid-state reactions and good quality crystal has been obtained. KGaSe₂ crystallizes in the monoclinic space group C2/c with cell dimensions of a = 10.878(2) Å, b = 10.872(2) Å, c = 15.380(3) Å, and β = 100.18(3)°. In the structure, adamantane like [Ga₄Se₁₀]⁸⁻ units are connected by common corners forming two-dimensional [GaSe₂]⁻ layers which are separated by K⁺ cations. KGaSe₂ exhibits congruent-melting behavior at around 965 °C. It is transparent in the range of 0.47–20.0 μm and has a band gap of 2.60(2) eV. From a band structure calculation, KGaSe₂ is a direct-gap semiconductor. The band gap is mainly determined by the [GaSe₂]⁻ layer.     

Synthesis and crystal structure of the first chain-type nitridosilicates RE5Si3N9 (RE = La,Ce)

The novel branched chain-type nitridosilicates Ce₅Si₃N₉ and La₅Si₃N₉ have been synthesized in a radio-frequency furnace starting from the respective metals and silicon diimide Si(NH)₂ at 1625 °C for La₅Si₃N₉ and 1650 °C for Ce₅Si₃N₉, respectively. The structure of Ce₅Si₃N₉ has been determined by single-crystal X-ray diffraction (Ce₅Si₃N₉, Cmca (no. 64), a = 10.567(2) Å, b = 11.329(2) Å, c = 15.865(3) Å, V = 1899.3 Å³, Z = 8, R₁ = 0.0391, 1480 independent reflections, 90 refined parameters). The structure of isotypic La₅Si₃N₉ has been refined by the Rietveld method, starting from single-crystal data of Ce₅Si₃N₉ (La₅Si₃N₉, Cmca (no. 64), a = 10.647(4) Å, b = 11.414(4) Å, c = 16.030(5) Å, V = 1948.1 Å³, Z = 8, R_P = 0.0348, R_F² = 0.0533). Both compounds are built up of alternating Q²- and Q³-type corner sharing SiN₄ tetrahedra with additional corner sharing Q¹-units attached to the Q³-tetrahedra pointing alternately in opposing directions. These zipper-like chains are intertwined in both directions perpendicular to the chain itself to form a three-dimensionally interlocked structure with the rare-earth ions situated between the chains. Magnetic measurements resulted in a ferromagnetic ground state with a magnetic moment in agreement with Ce³⁺.     

Lithium storage properties of Ti3C2Tx (Tx = F,Cl, Br) MXenes

In this work, Ti₃C₂T_x MXene with -F, -Cl and -Br surface terminations are synthesized and the effect of these halogen terminations on the lithium storage properties is investigated. A maximum Li⁺ storage capacity of 189 mAh/g is achieved with Ti₃C₂Br_x MXene much higher than Ti₃C₂Cl_x and Ti₃C₂F_x with 138 mAh/g and 123 mAh/g, respectively. Density functional theory (DFT) calculation shows that the adsorption formation energy of halogen atoms on Ti atoms follows the trend of Ti-F > Ti-Cl > Ti-Br, leading to the same trend in the content of terminations on corresponding MXenes. In addition, inevitable exposure of MXene to oxygen causes competition between halogen and oxygen. Theoretical results show Ti₃C₂Br_x MXene has the highest Ti to O ratio and the lowest Ti to Br ratio, the high lithium affinity of O explains the maximum Li-ion storage capacity with Ti₃C₂Br_x MXene. This work shed light on the opportunity for achieving improved lithium storage properties of MXene electrodes by regulating the surface chemistry.     

Synthesis,structure and characterization of a new trinuclear magnetic semiconductor PbI4[Cu(Me2dtc)(bipy)]2

A new trinuclear magnetic lead iodide semiconductor PbI₄[Cu(Me₂dtc)(bipy)]₂ (Me₂dtc = N,N-dimethyldithiocarbamate, bipy = 2,2′-bipyridine) has been synthesized, and structurally characterized by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group P2₁/c with a = 22.2137(11) Å, b = 11.3687(4) Å, c = 15.3382(8) Å, β = 102.372(3)°, Z = 4, V = 3783.6(3) Å³. It is built up by [PbI₄S₂] octahedron linked with two [CuIS₂N₂] square pyramids through common edges. The adjacent molecules stack with each other to form a two-dimensional (2D) layer along ab plane via the π–π stacking interactions between aromatic groups of bipy ligands. Then the 2D layers are further extended into a three-dimensional structure through hydrogen bonding interactions. The temperature dependence of the electrical conductivity indicates that this compound exhibits semiconducting character. The title brown–black compound has an optical bandgap of 1.26 eV, and the variable-temperature magnetic susceptibility measurement indicates weak antiferromagnetic behavior with J = ?1.06 cm^?1.     

Achieving high-rate capacitance of multi-layer titanium carbide (MXene) by liquid-phase exfoliation through Li-intercalation

The stacks of multi-layer Ti₃C₂T_x and other types of MXene materials limit their electrochemical performance. Herein, we report a facile exfoliation technique to improve the exfoliation efficiency through Li-intercalation into Ti₃C₂T_x interlayers in isopropyl alcohol (IPA) with LiOH as intercalant. This de-intercalation method presented here not only effectively delaminates the stacked Ti₃C₂T_x multi-layers into separate few-layer MXene sheets, but also achieves high-rate supercapacitive performance of Ti₃C₂T_x electrode. The as-produced delaminated Ti₃C₂T_x shows highly improved electrochemical capacitive properties from 47 to 115 F g^− 1 at 200 mV s^− 1. Even at extremely high scan rate of 1000 mV s^− 1, a specific capacitance of 82 F g^− 1 is still obtained. The high-rate capability can be attributed to improved ions accessibility into the few-layer structures. This study offers a new and simple exfoliation pathway for MXenes materials to exploit their full potential in energy storage applications.     

Two zincophosphite frameworks templated by 1,4-diaminobenzene: syntheses and structures of C6N2H10·Zn(HPO3)2 and (C6N2H8)0.5·ZnHPO3

The solution-mediated syntheses and single crystal structures of C₆N₂H₁₀·Zn(HPO₃)₂ (I) and (C₆N₂H₈)_0.5·ZnHPO₃ (II) are reported. Slight variation of the synthesis conditions led to two quite different phases. I contains infinite chains of ZnO₄ and HPO₃ groups with the protonated organic moiety acting as a template and interacting with the chains by NH⋯O hydrogen bonds and possible CH⋯O interactions. In II, the neutral 1,4-diamino benzene molecule bonds to Zn (as a ligand) and an unusual composite, “pillared”, structure results, with the organic species bridging 6³ polyhedral sheets, although NH⋯O bonds are also present. Similarities and differences to other zinc phosphites and phosphates are briefly discussed for I and II. Crystal data: C₆N₂H₁₀·Zn(HPO₃)₂, M_r=335.48, monoclinic, C2/c (No. 15), a=17.2471 (14) Å, b=9.0720 (8) Å, c=7.6529 (6) Å, β=103.752 (2)°, V=1163.09 (7) Å³, Z=4, R(F)=0.038, wR(F²)=0.084. (C₆N₂H₈)_0.5·ZnHPO₃, M_r=199.42, orthorhombic, Pbca (No. 61), a=8.0314 (16) Å, b=8.1299 (16) Å, c=18.830 (4) Å, V=1229.5 (4) Å³, Z=8, R(F)=0.026, wR(F²)=0.055.     

Ferroelectric and electrical properties of LiNaWO4 compound

The aim of this work is to elaborate the LiNaWO₄ compound, using the solid state method, then to characterize it using an XR study which confirms that it crystallizes in the orthorhombic system with P222 as space group and with the lattice parameters a = 12.82 Å, b = 17.49 Å, c = 7.25 Å and α = β = γ = 90°. The differential scanning calorimetry (DSC) shows two endothermic peaks at T₁ = 388 K and T₂ = 500 K. The first peak is detected by the dielectric study, attributed to a phase transition from a ferroelectric phase to a paraelectric one, while the second peak indicates the presence of a phase transition, confirmed later by the result of the electrical study. All modes pertaining to vibrations of WO₄^2? tetrahedral appear in the Raman spectrum. Moreover, its impedance response is modeled by a single cell formed by a parallel combination of R//C//CPE, i.e. the response of our compound is that of the grain. The variation of the σ_g and σ_dc, as a function of temperature, confirms the phase transition observed in the calorimetric study at T₂. The conduction mechanism in the two phases indicates that the first phase (I) is described by the CBH model and the second phase by the OLPT model.     

Synthesis,crystal growth and structure,magnetic and electrical properties of Ba4Ru2FeO10 and Ba4Ru2CoO10

Crystals of Ba₄Ru₂FeO₁₀ and Ba₄Ru₂CoO₁₀ (Cmca, Z = 4, Ba₄Ru₂FeO₁₀: a = 5.7899(1) Å, b = 13.2898(3) Å, c = 13.0098(4) Å, V = 1001.06 Å³; Ba₄Ru₂CoO₁₀: a = 5.7691(2) Å, b = 13.2061(3) Å, c = 12.9755(4) Å, V = 988.57 Å³) were obtained from binary oxides and BaCoO₃ at 1300 °C. Both compounds crystallize isostructural to Ba₄Ru₃O₁₀ with different preference of the 3d metal at the two crystallographic sites of Ru in the parent compound. Ba₄Ru₂FeO₁₀ exhibits a spin-glass like transition at 25 K, while Ba₄Ru₂CoO₁₀ does not show any magnetic order down to 2 K. According to electrical resistivity measurements performed on single crystals both compounds are semiconductors. In contrast to the variable-range hopping of the transport mechanism of Co bearing material, the electrical resistivity of Ba₄Ru₂FeO₁₀ follows an activation law resulting in a band gap of approximately 0.98 eV.     

A new type of orthoborates: ASr4La3(BO3)6 (A = Li,Na)

Two new rare earth containing orthoborate crystals ASr₄La₃(BO₃)₆ (A = Li, Na) have been obtained by spontaneous nucleation from high-temperature melts of A₂O–SrO–La₂O₃–B₂O₃–AF. X-ray diffraction analyses show that they both crystallize in the rhombohedral space group R-3 with cell parameters of a = 12.309(7) Å, c = 9.316(7) Å and a = 12.4049(13) Å, c = 9.348(2) Å for the Li and Na compounds respectively. Similar to the large A′₆MM′(BO₃)₆ family, these compounds are all related to the structure of Sr₃Y(BO₃)₃ with La and Sr statistically occupy the Sr site, and the alkaline elements and remaining Sr enter the ordered Y1 and Y2 sites, which can be approximately represented as (La_2.91Sr_3.09)(La_0.09Sr_0.91)Li[B₆O₁₈] and (La_2.85Sr_3.15)(La_0.15Sr_0.85)Na[B₆O₁₈]. The characteristic of the structure is that the La/Sr and isolated BO₃ groups form a network with tunnels along the c-axis where the alkaline A and Sr ions alternatively reside. The optical transmission spectrum shows that the ultraviolet absorption edge of NaSr₄La₃(BO₃)₆ crystal is about 193 nm and Raman spectra reveal that both crystals possess sharp peaks at 930 cm⁻¹.     

Crystal structures and magnetic properties of the honeycomb-lattice antiferromagnet M2(pymca)3(ClO4), (M = Fe,Co, Ni)

We report on the syntheses, crystal structures, and magnetic properties of a series of transition metal coordination polymers M₂(pymca)₃(ClO₄), (pymca = pyrimidine-2-carboxylic acid, M = Fe (1), Co (2), and Ni (3)). These compounds are found to crystallize in a trigonal crystal system, space group P31m, with the lattice constants a = 9.727 Å and c = 5.996 Å for 1, a = 9.608 Å and c = 5.996 Å for 2, and a = 9.477 Å and c = 5.958 Å for 3 at room temperature. In these compounds, each pymca ligand connects to two M²⁺ ions, forming a honeycomb network in the ab plane. The temperature dependences of magnetic susceptibilities in these compounds show broad maxima, indicating antiferromagnetic interactions within two-dimensional honeycomb layers. We also observed an antiferromagnetic phase transition at low temperatures by magnetic susceptibility and heat capacity measurements. From the crystal structures and magnetic properties, we conclude that the compounds 1, 2, and 3 are good realizations of honeycomb-lattice antiferromagnets.     

(R)‐1‐Phenyl­ethyl­ammonium 6‐amino‐5‐nitro­pyrimidine‐2,4(1H,3H)‐dionate (R)‐1‐phenyl­ethyl­amine hemisolvate: hydrogen‐bonded sheets of ions with pendent solvent mol­ecules

In the title compound, 2C₈H₁₂N⁺·2C₄H₃N₄O₄⁻·C₈H₁₁N, the anions are linked by paired N—H⋯N hydrogen bonds [H⋯N = 2.07 and 2.11 Å, N⋯N = 2.942 (3) and 2.978 (3) Å and N—H⋯N = 173 and 170°] and by paired N—H⋯O hydrogen bonds [H⋯O = 1.98 and 2.05 Å, N⋯O = 2.855 (3) and 2.917 (3) Å, and N—H⋯O = 173 and 167°] into chains of rings. These chains are linked into sheets by further N—H⋯O hydrogen bonds in which all of the donors are provided by the cations [H⋯O = 1.83–2.17 Å, N⋯O = 2.747 (3)–2.965 (3) Å and N—H⋯O = 141–168°]. The neutral amine molecule is pendent from the sheet and is linked to it by a single N—H⋯N hydrogen bond [H⋯N = 2.00 Å, N⋯N = 2.901 (3) Å and N—H⋯N = 175°].