Syntheses, structures, and vibrational spectroscopy of the two-dimensional iodates Ln(IO3)3 and Ln(IO3)3(H2O) (LnYb, Lu)

The reaction of Lu³⁺ or Yb³⁺ and H₅IO₆ in aqueous media at 180 °C leads to the formation of Yb(IO₃)₃(H₂O) or Lu(IO₃)₃(H₂O), respectively, while the reaction of Yb metal with H₅IO₆ under similar reaction conditions gives rise to the anhydrous iodate, Yb(IO₃)₃. Under supercritical conditions Lu³⁺ reacts with HIO₃ and KIO₄ to yield the isostructural Lu(IO₃)₃. The structures have been determined by single-crystal X-ray diffraction. Crystallographic data are (MoKα, λ=0.71073 Å): Yb(IO₃)₃, monoclinic, space group P2₁/n, a=8.6664(9) Å, b=5.9904(6) Å, c=14.8826(15) Å, β=96.931(2)°, V=766.99(13), Z=4, R(F)=4.23% for 114 parameters with 1880 reflections with I>2σ(I); Lu(IO₃)₃, monoclinic, space group P2₁/n, a=8.6410(9), b=5.9961(6), c=14.8782(16) Å, β=97.028(2)°, V=765.08(14), Z=4, R(F)=2.65% for 119 parameters with 1756 reflections with I>2σ(I); Yb(IO₃)₃(H₂O), monoclinic, space group C2/c, a=27.2476(15), b=5.6296(3), c=12.0157(7) Å, β=98.636(1)°, V=1822.2(2), Z=8, R(F)=1.51% for 128 parameters with 2250 reflections with I>2σ(I); Lu(IO₃)₃(H₂O), monoclinic, space group C2/c, a=27.258(4), b=5.6251(7), c=12.0006(16) Å, β=98.704(2)°, V=1818.8(4), Z=8, R(F)=1.98% for 128 parameters with 2242 reflections with I>2σ(I). The f elements in all of the compounds are found in seven-coordinate environments and bridged with monodentate, bidentate, or tridentate iodate anions. Both Lu(IO₃)₃(H₂O) and Yb(IO₃)₃(H₂O) display distinctively different vibrational profiles from their respective anhydrous analogs. Hence, the Raman profile can be used as a complementary diagnostic tool to discern the different structural motifs of the compounds.     

New one-dimensional uranyl and neptunyl iodates: crystal structures of K3[(UO2)2(IO3)6](IO3)·H2O and K[NpO2(IO3)3]·1.5H2O

The uranyl and neptunyl(VI) iodates, K₃[(UO₂)₂(IO₃)₆](IO₃)·H₂O (1) and K[NpO₂(IO₃)₃]·1.5H₂O (2), have been prepared and crystallized under mild hydrothermal conditions. The structures of 1 and 2 both contain one-dimensional _∞¹[AnO₂(IO₃)₃]¹⁻(An=U,Np) ribbons that consist of approximately linear actinyl(VI) cations bound by iodate anions to yield AnO₇ pentagonal bipyramids. The AnO₇ units are linked by bridging iodate anions to yield chains that are in turn coupled by additional iodate anions to yield ribbons. The edges of the ribbons are terminated by monodentate iodate anions. For 1 and 2, K⁺ cations and water molecules separate the ribbons from one another. In addition, isolated iodate anions are also found between _∞¹[UO₂(IO₃)₃]¹⁻ ribbons in 1. In order to aid in the assignment of oxidation states in neptunyl containing compounds, a bond-valence sum parameter of 2.018 Å for Np(VI) bound exclusively to oxygen has been developed with b=0.37 Å. Crystallographic data (193 K, MoKα, λ=0.71073): 1, triclinic, , a=7.0609(4) Å, b=14.5686(8)  Å, c=14.7047(8)  Å, α=119.547(1)°, β=95.256(1)°, γ=93.206(1)°, Z=2, R(F)=2.49% for 353 parameters with 6414 reflections with I>2σ(I); (203 K, MoKα, λ=0.71073): 2, monoclinic, P2₁/c, a=7.796(4)  Å, b=7.151(3)  Å, c=21.79(1)  Å, β=97.399(7)°, Z=4, R(F)=6.33% for 183 parameters with 2451 reflections with I>2σ(I).     

Two new octahedral/pyramidal frameworks containing both cation channels and lone-pair channels: syntheses and structures of Ba2MnMn2(SeO3)6 and PbFe2(SeO3)4

The hydrothermal syntheses, single crystal structures, and some properties of Ba₂Mn^IIMn₂^III(SeO₃)₆ and PbFe₂(SeO₃)₄ are reported. These related phases contain three-dimensional frameworks of vertex (FeO₆) and vertex/edge linked (MnO₆) octahedra and SeO₃ pyramids. In each case, the MO₆/SeO₃ framework encloses two types of 8 ring channels, one of which encapsulates the extra-framework cations and one of which provides space for the Se^IV lone pairs. Crystal data: Ba₂Mn₃(SeO₃)₆, M_r=1201.22, monoclinic, P2₁/c (No. 14), a=5.4717 (3) Å, b=9.0636 (4) Å, c=17.6586 (9) Å, β=94.519 (1)°, V=873.03 (8) Å³, Z=2, R(F)=0.031, wR(F²)=0.070; PbFe₂(SeO₃)₄, M_r=826.73, triclinic, (No. 2), a=5.2318 (5) Å, b=6.7925 (6) Å, c=7.6445 (7) Å, α=94.300 (2)°, β=90.613 (2)°, γ=95.224 (2)°, V=269.73 (4) Å³, Z=1, R(F)=0.051, wR(F²)=0.131.     

Synthesis and characterization of two-dimensional fluorinated metal phosphates incorporating 2,2′-bipyridine ligands: M2F2(2,2′-bpy)(HPO4)2(H2O) (M=Fe, Ga)

Two fluorinated metal phosphates, M₂F₂(2,2′-bpy)(HPO₄)₂(H₂O) (M=Fe, Ga), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic susceptibility. The two compounds are isostructural and crystallize in the triclinic space group , a=7.6595(8)Å, b=10.101(1)Å, c=11.260(1)Å, α=107.555(2)°, β=105.174(2)°, γ=98.975(2)°, V=775.1(2)ų and Z=2 for the Fe compound, and a=7.5816(6)Å, b=9.9943(7)Å, c=11.1742(8)Å, α=107.333(1)°, β=105.014(1)°, γ=99.261(1)° and V=754.2(2)ų for the Ga compound. They are the first fluorinated metal phosphates which incorporate 2,2′-bipyridine ligands. The structure consists of edge-sharing octahedral dimers with the composition Fe₂F₄(H₂O)₂O₄ and discrete FeN₂O₄ octahedra, which are linked into two-dimensional sheets through corner-sharing phosphate tetrahedra. The 2,2′-bpy ligands bind in a bidentate fashion to the metal atoms and project into interlamellar region. The layers are extended into a three-dimensional supramolecular array via π-π stacking interactions of the 2,2′-bpy ligands. Magnetic susceptibility of the iron compound confirms the presence of Fe^III.     

Synthesis, crystal structure and mono-dimensional thallium ion conduction of TlFe0.22Al0.78As2O7

A new solid solution TlFe_0.22Al_0.78As₂O₇ has been synthesized by a solid-state reaction. The structure of the title compound has been determined from a single-crystal X-ray diffraction and refined to final values of the reliability factors: R(F²)=0.030 and wR(F²)=0.081 for 1343 independent reflections with I>2σ(I). It crystallizes in the triclinic space group P-1, with a=6.296(2) Å, b=6.397(2) Å, c=8.242(2) Å, α=96.74(2)°, β=103.78(2)°, γ=102.99(3)°, V=309.0(2) Å³ and Z=2. The structure can be described as a three-dimensional framework containing (Fe/Al)O₆ octahedra connected through As₂O₇ groups. The metallic units and diarsenate groups share oxygen corners to form a three-dimensional framework with interconnected tunnels parallel to the a, b and c directions, where Tl⁺ cations are located. The ionic conductivity measurements are performed on pellets of the polycrystalline powder. At 683 K, The conductivity value is 5.23×10⁻⁶ S cm⁻¹ and the ionic jump activation energy is 0.656 eV. The bond valence analysis reveals that the ionic conductivity is ensured by Tl⁺ along the [001] direction.     

Hydrothermal syntheses and structures of two novel vanadium selenites, {[VO(OH)(H2O)](SeO3)}4·2H2O and (H3NCH2CH2NH3)[(VO)(SeO3)2]

Two novel vanadium selenites {[VO(OH)(H₂O)](SeO₃)}₄·2H₂O 1 and (H₃NCH₂CH₂NH₃)[(VO)(SeO₃)₂] 2 were synthesized by hydrothermal method and their crystal structures were determined by single-crystal X-ray diffraction. It is characterized by inductively coupled plasma (ICP), thermogravimetric (TG) and elemental analyses. Compound 1 crystallizes in the monoclinic system, space group C2/c, a=21.2250(11) Å, b=12.6309(6) Å, c=17.0249(10) Å, β=96.830(3)°, V=4531.8(4) Å³ and Z=8, R₁ [I>2σ(I)]=0.0344, wR₂ [I>2σ(I)]=0.119; Compound 2 crystallizes in the monoclinic system, space group P2₁/c, a=9.6389(4) Å, b=6.9922(3) Å, c=15.0324(5) Å, β=102.297(2)°, V=989.90(7) Å³ and Z=4, R₁ [I>2σ(I)]=0.0452, wR₂ [I>2σ(I)]=0.117. {[VO(OH)(H₂O)](SeO₃)}₄·2H₂O has a 1D structure constructed from the {[VO(OH)(H₂O)](SeO₃)}_∞ chains. (H₃NCH₂CH₂NH₃)[(VO)(SeO₃)₂] has a layered structure composed of alternating VO₅ and SeO₃ units with protonated ethylenediamine as interlayer guest.     

Hydrothermal synthesis, structure, and magnetic properties of Pu(SeO3)2

The reaction between PuO₂ and SeO₂ under mild hydrothermal conditions results in the formation of Pu(SeO₃)₂ as brick-red prisms. This compound adopts the Ce(SeO₃)₂ structure type, and consists of one-dimensional chains of edge-sharing [PuO₈] distorted bicapped trigonal prisms linked by [SeO₃] units into a three-dimensional network. Crystallographic data: Pu(SeO₃)₂, monoclinic, space group P2₁/n, a=6.960(1) Å, b=10.547(2) Å, c=7.245(1) Å, β=106.880(9)°, V=508.98(17) Å³, Z=4 (T=193 K), R(F)=2.92% for 83 parameters with 1140 reflections with I>2σ(I). Magnetic susceptibility data for Pu(SeO₃)₂ are linear from 35 to 320 K and yield an effective moment of 2.71(5) μ_B and a Weiss constant of −500(5) K.     

Synthesis and structural investigation of the compounds containing HF2 anions: Ca(HF2)2, Ba4F4(HF2)(PF6)3 and Pb2F2(HF2)(PF6)

Three new compounds Ca(HF₂)₂, Ba₄F₄(HF₂)(PF₆)₃ and Pb₂F₂(HF₂)(PF₆) were obtained in the system metal(II) fluoride and anhydrous HF (aHF) acidified with excessive PF₅. The obtained polymeric solids are slightly soluble in aHF and they crystallize out of their aHF solutions. Ca(HF₂)₂ was prepared by simply dissolving CaF₂ in a neutral aHF. It represents the second known compound with homoleptic HF environment of the central atom besides Ba(H₃F₄)₂. The compounds Ba₄F₄(HF₂)(PF₆)₃ and Pb₂F₂(HF₂)(PF₆) represent two additional examples of the formation of a polymeric zigzag ladder or ribbon composed of metal cation and fluoride anion (MF⁺)_n besides PbF(AsF₆), the first isolated compound with such zigzag ladder. The obtained new compounds were characterized by X-ray single crystal diffraction method and partly by Raman spectroscopy. Ba₄F₄(HF₂)(PF₆)₃ crystallizes in a triclinic space group P1¯ with a=4.5870(2) Å, b=8.8327(3) Å, c=11.2489(3) Å, α=67.758(9)°, β=84.722(12), γ=78.283(12)°, V=413.00(3) Å³ at 200 K, Z=1 and R=0.0588. Pb₂F₂(HF₂)(PF₆) at 200 K: space group P1¯, a=4.5722(19) Å, b=4.763(2) Å, c=8.818(4) Å, α=86.967(10)°, β=76.774(10)°, γ=83.230(12)°, V=185.55(14) ų, Z=1 and R=0.0937. Pb₂F₂(HF₂)(PF₆) at 293 K: space group P1¯, a=4.586(2) Å, b=4.781(3) Å, c=8.831(5) Å, α=87.106(13)°, β=76.830(13)°, γ=83.531(11)°, V=187.27(18) Å³, Z=1 and R=0.072. Ca(HF₂)₂ crystallizes in an orthorhombic Fddd space group with a=5.5709(6) Å, b=10.1111(9) Å, c=10.5945(10) Å, V=596.77(10) Å³ at 200 K, Z=8 and R=0.028.     

(C6H17N3)[Zn4(PO4)2(HPO3)2]: a new layered zinc phosphate-phosphite templated by 1-(2-Aminoethyl) piperazine

Employing 1-(2-Aminoethyl) piperazine as a template, a new organically templated layered zinc phosphate-phosphite (C₆H₁₇N₃)[Zn₄(PO₄)₂(HPO₃)₂] has been prepared hydrothermally. Single-crystal X-ray diffraction analysis shows that it crystallizes in the monoclinic space group Cc with a=5.3272(11) Å, b=17.146(3) Å, c=22.071(4) Å, β=94.58(3)°, V=2009.5(7) Å³, Z=4, R₁=0.0201 (I>2σ(I)) and wR₂=0.0812 (all data). The inorganic network is based on strictly alternating ZnO₄ tetrahedral units and P-centered units including PO₄ tetrahedra and HPO₃ pseudo-pyramids forming a double layered structure that contains columns of double six-membered rings. The diprotonated 1-(2-Aminoethyl) piperazine molecules reside in the interlayer region and interact with the inorganic network through H-bonds.     

Synthesis, structure of [H3dien]·(MF6)·H2O (M=Cr, Fe) and Fe Mössbauer study of [H3dien]·(FeF6)·H2O

Single crystals of [H₃dien]·(FeF₆)·H₂O (I) and [H₃dien]·(CrF₆)·H₂O (II) are obtained by solvothermal synthesis under microwave heating. I is orthorhombic (Pna2₁) with a=11.530(2) Å, b=6.6446(8) Å, c=13.787(3) Å, V=1056.3(2) Å³ and Z=4. II is monoclinic (P2₁/c) with a=13.706(1) Å, b=6.7606(6) Å, c=11.3181(9) Å, β=99.38(1)°, V=1034.7(1) Å³ and Z=4. The structure determinations, performed from single crystal X-ray diffraction data, lead to the R₁/wR₂ reliability factors 0.028/0.066 for I and 0.035/0.102 for II. The structures of I and II are built up from isolated FeF₆ or CrF₆ octahedra, water molecules and triprotonated amines. In both structures, each octahedron is connected by hydrogen bonds to six organic cations and two water molecules. The iron-based compound is also characterized by ⁵⁷Fe Mössbauer spectrometry: the hyperfine structure confirms the presence of Fe³⁺ in octahedral coordination and reveals the existence of paramagnetic spin fluctuations.     

Syntheses, structures, and properties of Ag4(Mo2O5)(SeO4)2(SeO3) and Ag2(MoO3)3SeO3

Ag₄(Mo₂O₅)(SeO₄)₂(SeO₃) has been synthesized by reacting AgNO₃, MoO₃, and selenic acid under mild hydrothermal conditions. The structure of this compound consists of cis-MoO₂²⁺ molybdenyl units that are bridged to neighboring molybdenyl moieties by selenate anions and by a bridging oxo anion. These dimeric units are joined by selenite anions to yield zigzag one-dimensional chains that extended down the c-axis. Individual chains are polar with the C₂ distortion of the Mo(VI) octahedra aligning on one side of each chain. However, the overall structure is centrosymmetric because neighboring chains have opposite alignment of the C₂ distortion. Upon heating Ag₄(Mo₂O₅)(SeO₄)₂(SeO₃) looses SeO₂ in two distinct steps to yield Ag₂MoO₄. Crystallographic data: (193 K; MoKα, λ=0.71073 Å): orthorhombic, space group Pbcm, a=5.6557(3), b=15.8904(7), c=15.7938(7) Å, V=1419.41(12), Z=4, R(F)=2.72% for 121 parameters with 1829 reflections with I>2σ(I). Ag₂(MoO₃)₃SeO₃ was synthesized by reacting AgNO₃ with MoO₃, SeO₂, and HF under hydrothermal conditions. The structure of Ag₂(MoO₃)₃SeO₃ consists of three crystallographically unique Mo(VI) centers that are in 2+2+2 coordination environments with two long, two intermediate, and two short bonds. These MoO₆ units are connected to form a molybdenyl ribbon that extends along the c-axis. These ribbons are further connected together through tridentate selenite anions to form two-dimensional layers in the [bc] plane. Crystallographic data: (193 K; MoKα, λ=0.71073 Å): monoclinic, space group P2₁/n, a=7.7034(5), b=11.1485(8), c=12.7500(9) Å, β=105.018(1) V=1002.7(2), Z=4, R(F)=3.45% for 164 parameters with 2454 reflections with I>2σ(I). Ag₂(MoO₃)₃SeO₃ decomposes to Ag₂Mo₃O₁₀ on heating above 550 °C.     

Synthesis and crystal structure of a new open-framework iron phosphate (NH4)4Fe3(OH)2F2[H3(PO4)4]: Novel linear trimer of corner-sharing Fe(III) octahedra

A new iron phosphate (NH₄)₄Fe₃(OH)₂F₂[H₃(PO₄)₄] has been synthesized hydrothermally at HF concentrations from 0.5 to 1.2 mL. Single-crystal X-ray diffraction analysis reveals its three-dimensional open-framework structure (monoclinic, space group P2₁/n (No. 14), a=6.2614(13) Å, b=9.844(2) Å, c=14.271(3) Å, β=92.11(1)°, V=879.0(3) Å³). This structure is built from isolated linear trimers of corner-sharing Fe(III) octahedra, which are linked by (PO₄) groups to form ten-membered-ring channels along [1 0 0]. This isolated, linear trimer of corner-sharing Fe(III) octahedra, [(FeO₄)₃(OH)₂F₂], is new and adds to the diverse linkages of Fe polyhedra as secondary building units in iron phosphates. The trivalent iron at octahedral sites for the title compound has been confirmed by synchrotron Fe K-edge XANES spectra and magnetic measurements. Magnetic measurements also show that this compound exhibit a strong antiferromagnetic exchange below T_N=17 K, consistent with superexchange interactions expected for the linear trimer of ferric octahedra with the Fe-F-Fe angle of 132.5°.     

Syntheses and single-crystal structures of CsTh(MoO4)2Cl and Na4Th(WO4)4

Colorless crystals of CsTh(MoO₄)₂Cl and Na₄Th(WO₄)₄ have been synthesized at 993 K by the solid-state reactions of ThO₂, MoO₃, CsCl, and ThCl₄ with Na₂WO₄. Both compounds have been characterized by the single-crystal X-ray diffraction. The structure of CsTh(MoO₄)₂Cl is orthorhombic, consisting of two adjacent [Th(MoO₄)₂] layers separated by an ionic CsCl sublattice. It can be considered as an insertion compound of Th(MoO₄)₂ and reformulated as Th(MoO₄)₂·CsCl. The Th atom coordinates to seven monodentate MoO₄ tetrahedra and one Cl atom in a highly distorted square antiprism. Na₄Th(WO₄)₄ adopts a scheelite superlattice structure. The three-dimensional framework of Na₄Th(WO₄)₄ is constructed from corner-sharing ThO₈ square antiprisms and WO₄ tetrahedra. The space within the channels is filled by six-coordinate Na ions. Crystal data: CsTh(MoO₄)₂Cl, monoclinic, P2₁/c, Z=4, a=10.170(1) Å, b=10.030(1) Å, c=9.649(1) Å, β=95.671(2)°, V=979.5(2) Å³, R(F)=2.65% for I>2σ(I); Na₄Th(WO₄)₄, tetragonal, I4₁/a, Z=4, a=11.437(1) Å, c=11.833(2) Å, V=1547.7(4) Å³, R(F)=3.02% for I>2σ(I).     

Hydrothermal synthesis and characterization of a new iron phosphate structure of ladder-like chains and coordination directly by an organo-nitrogen ligand: [Fe(phen)(HPO4)(H2PO4)·0.5H2O] (phen=1,10-phenanthroline)

A coordination iron phosphate, Fe(phen)(HPO₄)(H₂PO₄)·0.5H₂O (I), has been hydrothermally synthesized and characterized by elemental analysis, IR spectral analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group C2/m (No. 12), with cell parameters M=438.03, a=21.421(5) Å, b=6.4292(1) Å, c=12.190(3) Å, β=105.964(9)°, V=1614.1(6) Å³, Z=4, R₁[I>2σ(I)]=0.0545, wR₂[I>2σ(I)]=0.1186. This compound displays a new structure of ladder-like chains, in which each one-dimensional chain is constituted by the distorted octahedral units of Fe³⁺ bridged through PO₄ tetrahedron. The phen ligands in the compound bind in a bidentate fashion to the metal atoms and the ladder-like structure of the compound extends into a three-dimensional supramolecular array via π-π stacking interactions of phen ligands. Mössbauer spectroscopy shows the presence of Fe³⁺ in the octahedral coordination. Magnetic susceptibility measurement studies show that this material may model as anti-ferromagnetic.     

Synthesis and structure of [C6H14N2][(UO2)4(HPO4)2(PO4)2(H2O)]·H2O: An expanded open-framework amine-bearing uranyl phosphate

A new open-framework compound, [C₆H₁₄N₂][(UO₂)₄(HPO₄)₂(PO₄)₂(H₂O)]·H₂O, (DUP-1) has been synthesized under mild hydrothermal conditions. The resulting structure consists of diprotonated DABCOH₂²⁺ (C₆H₁₄N₂²⁺) cations and occluded water molecules occupying the channels of a complex uranyl phosphate three-dimensional framework. The anionic lattice contains uranophane-like sheets connected by hydrated pentagonal bipyramidal UO₇ units. [C₆H₁₄N₂][(UO₂)₄(HPO₄)₂(PO₄)₂(H₂O)]·H₂O possesses five crystallographically unique U centers. U(VI) is present here in both six- and seven-coordinate environments. The DABCOH₂²⁺ cations are held within the channels by hydrogen bonds to both two uranyl oxygen atoms and a μ₂-O atom. Crystallographic data (193 K, Mo Kα, λ=0.71073 Å): DUP-1, monoclinic, P2₁/n, a=7.017(1) Å, b=21.966(4) Å, c=17.619(3) Å, β=90.198(3)°, Z=4, R(F)=4.76% for 382 parameters with 6615 reflections with I>2σ(I).     

Magnetism and Raman spectroscopy of the dimeric lanthanide iodates Ln(IO3)3 (Ln=Gd, Er) and magnetism of Yb(IO3)3

Colorless single crystals of Gd(IO₃)₃ or pale pink single crystals of Er(IO₃)₃ have been formed from the reaction of Gd metal with H₅IO₆ or Er metal with H₅IO₆ under hydrothermal reaction conditions at 180 °C. The structures of both materials adopt the Bi(IO₃)₃ structure type. Crystallographic data are (MoKα, λ=0.71073 Å): Gd(IO₃)₃, monoclinic, space group P2₁/n, a=8.7615(3) Å, b=5.9081(2) Å, c=15.1232(6) Å, β=96.980(1)°, V=777.03(5) Z=4, R(F)=1.68% for 119 parameters with 1930 reflections with I>2σ(I); Er(IO₃)₃, monoclinic, space group P2₁/n, a=8.6885(7) Å, b=5.9538(5) Å, c=14.9664(12) Å, β=97.054(1)°, V=768.4(1) Z=4, R(F)=2.26% for 119 parameters with 1894 reflections with I>2σ(I). In addition to structural studies, Gd(IO₃)₃, Er(IO₃)₃, and the isostructural Yb(IO₃)₃ were also characterized by Raman spectroscopy and magnetic property measurements. The results of the Raman studies indicated that the vibrational profiles are adequately sensitive to distinguish between the structures of the iodates reported here and other lanthanide iodate systems. The magnetic measurements indicate that only in Gd(IO₃)₃ did the 3+ lanthanide ion exhibit its full 7.9 μ_B Hund's rule moment; Er³⁺ and Yb³⁺ exhibited ground state moments and gap energy scales of 8.3 μ_B/70 K and 3.8 μ_B/160 K, respectively. Er(IO₃)₃ exhibited extremely weak ferromagnetic correlations (+0.4 K), while the magnetic ions in Gd(IO₃)₃ and Yb(IO₃)₃ were fully non-interacting within the resolution of our measurements (∼0.2 K).     

Synthesis, X-ray crystal structure and vibrational spectroscopy of the acidic pyrophosphate KMg0.5H2P2O7·H2O

The hydrated potassium hemimagnesium dihydrogen pyrophosphate KMg_0.5H₂P₂O₇·H₂O was synthesized. It crystallizes in the triclinic system, space group (n. 2), Z=2, with the following unit-cell parameters: a=6.8565(2) Å, b=7.3621(3) Å, c=7.6202(3) Å, α=81.044(2)°, β=72.248(2)°, γ=83.314(3)°, V=360.90(2) Å³. The structure was obtained by single-crystal X-ray diffractometry, and a full-matrix least-squares refinement based on F² gave a final R index of =0.0368 (wR=0.0975), utilizing 1446 observed reflections with I>2σ(I). The crystal packing consists in a three-dimensional network made by layers parallel to ab plane of PO₄ double tetrahedra and MgO₆ octahedra, linked by hydrogen bonds, while K atoms form complex coordination within cavities between tetrahedra and octahedra. The dihydro-pyrophosphate anion (H₂P₂O₇)²⁻ shows bent eclipsed conformation and the Mg²⁺ ion lies on inversion center. No coincidences observed between most of infrared and Raman spectral bands confirmed the centrosymmetric structure of the title compound; the vibrational spectra point to a bent POP bridge angle.     

Synthesis, characterization and magnetic property of a new 3D iron phosphite: |C4N3H14|[Fe3(HPO3)4F2(H2O)2] with intersecting channels

A new open-framework iron (III) phosphite |C₄N₃H₁₄|[Fe₃(HPO₃)₄F₂(H₂O)₂] has been solvothermally synthesized by using diethylenetriamine (DETA) as the structure-directing agent. Single-crystal X-ray diffraction analysis reveals that the compound crystallizes in the monoclinic space group C2/c having unit cell parameters a=12.877(3) Å, b=12.170(2) Å, c=12.159(2) Å, β=93.99(3)°, V=1900.9(7) Å³, and Z=4 with R₁=0.0447, wR₂=0.0958. The complex structure consists of HPO₃ pseudo-tetrahedra and {Fe₃O₁₄F₂} trimer building units. The assembly of these building units generates 3D inorganic framework with intersecting 6-, 8-, and 10-ring channels. The DETA cations are located in the 10-ring channels linked by hydrogen bonds. The Mössbauer spectrum shows that there exhibit two crystallographically independent iron (III) atoms. And the magnetic investigation shows the presence of antiferromagnetic interactions. Further characterization of the title compound was performed using X-ray powder diffraction (XRD), infrared (IR) spectra, thermal gravimetric analyses (TGA), inductively coupled plasma (ICP) and elemental analyses.     

New alkali-metal-molybdenum(VI)-selenium(IV) oxides: syntheses, structures, and characterization of A2SeMoO6 (A=Na, K, or Rb)

Three new quaternary selenites, A₂SeMoO₆ (A=Na⁺, K⁺, or Rb⁺), were synthesized through the solid-state reaction of A₂MoO₄ with SeO₂ at 400°C. Although the reported materials are ‘stoichiometrically equivalent’, the compounds exhibit strikingly different crystal structures. Whereas Na₂SeMoO₆ has a three-dimensional crystal structure, K₂SeMoO₆ and Rb₂SeMoO₆ are molecular and uni-dimensional, respectively. However, all of the new materials have structures containing Mo⁶⁺ octahedra linked to Se⁴⁺ trigonal pyramids. Although the Mo⁶⁺ and Se⁴⁺ cations are in local asymmetric environments in all three materials, only Na₂SeMoO₆ is non-centrosymmetric. Single crystal X-ray data: Na₂SeMoO₆, cubic, space group, P2₁3 (no. 198), a=8.375(5) Å, Z=4, R(F)=0.0143; K₂SeMoO₆, monoclinic, space group, P2₁/c (no. 14), a=6.118(8) Å, b=15.395(2) Å, c=7.580(9) Å, β=112.39(4)°, Z=4, R(F)=0.0281; Rb₂SeMoO₆, orthorhombic, space group, Pnma (no. 62), a=7.805(9) Å, b=6.188(7) Å, c=14.405(4) Å, Z=4, R(F)=0.0443.