Hydrothermal synthesis, structural characterization and magnetic studies of the new pillared microporous ammonium Fe(III) carboxyethylphosphonate: [NH4][Fe2(OH){O3P(CH2)2CO2}2]

The preparation by hydrothermal reaction and the crystal structure of the iron(III) carboxyethylphosphonate of formula [NH₄][Fe₂(OH){O₃P(CH₂)₂CO₂}₂] is reported. The green-yellow compound crystallizes in the monoclinic system, space group Pc(n.7), with the following unit-cell parameters: a=7.193(3) Å, b=9.776(3) Å, c=10.17(4) Å and β=94.3(2)°. It shows a typical layered hybrid organic-inorganic structure featuring an alternation of organic and inorganic layers along the a-axis of the unit cell. The bifunctional ligand [O₃P(CH₂)₂CO₂]³⁻ is deprotonated and acts as a linker between adjacent inorganic layers, to form pillars along the a-axis. The inorganic layers are made up of dinuclear Fe(III) units, formed by coordination of the metal ions with the oxygen atoms originating from the [O₃P−]²⁻ end of the carboxyethylphosphonate molecules, the oxygen atoms of the [−CO₂]⁻ end group of a ligand belonging to the adjacent layer and the oxygen atom of the bridged OH group. Each Fe(III) ion is six-coordinated in a very distorted octahedral environment. Within the dimer the Fe-Fe separation is found to be 3.5 Å, and the angle inside the [Fe(1)-O(11)-Fe(2)] dimers is ∼124°. The resulting 3D framework contains micropores delimited by four adjacent dimers in the (bc) planes of the unit cell. These holes develop along the a-direction as tunnel-like pores and [NH₄]⁺ cations are located there. The presence of the μ-hydroxo-bridged [Fe(1)-O(11)-Fe(2)] dimers in the lattice is also responsible for the magnetic behavior of the compound at low temperatures. The compound contains Fe³⁺ ions in the high-spin state and the two Fe(III) ions are antiferromagnetic coupled. The J/k value of −16.3 K is similar to those found for other μ-hydroxo-bridged Fe(III) dimeric systems having the same geometry.     

Orientation disorder in ammonium elpasolites: Crystal structures of (NH4)3AlF6, (NH4)3TiOF5 and (NH4)3FeF6

Crystal structures of the known (NH₄)₃AlF₆(I) and (NH₄)₃FeF₆(III) and new (NH₄)₃TiOF₅(II) elpasolites were refined by localizing anions (F⁻, O²⁻) in four acceptable positions of the cubic system Fm3m (Z=4) with a=8.9401(3), 9.1104(3), 9.110(1) Å, respectively. According to the refinement data and a rather large entropy change due to fluorine (oxygen) octahedra disordering in the above compounds and in (NH₄)₃WO₃F₃(IV) elpasolite, it was found that fluorine (oxygen) atoms are randomly distributed in two ways, in general 192l position or in mixed 24e + 96j one. Statistics in fluorine (oxygen) distribution is, probably, the result of domain structure of the crystals.     

Phase transitions and molecular motions in [Ni(ND3)6](ClO4)2

[Ni(ND₃)₆](ClO₄)₂ has three solid phases between 100 and 300 K. The phase transitions temperatures at heating (T_C1^h=164.1 K and T_C2^h=145.1 K) are shifted, as compared to the non-deuterated compound, towards the lower temperature of ca. 8 and 5 K, respectively. The ClO₄⁻ anions perform fast, picosecond, isotropic reorientation with the activation energy of 6.6 kJ mol⁻¹, which abruptly slow down at T_C1^c phase transition, during sample cooling. The ND₃ ligands perform fast uniaxial reorientation around the Ni-N bond in all three detected phases, with the effective activation energy of 2.9 kJ mol⁻¹. The reorientational motion of ND₃ is only slightly distorted at the T_C1 phase transition due to the dynamical orientational order-disorder process of anions. The low value of the activation energy for the ND₃ reorientation suggests that this reorientation undergoes the translation-rotation coupling, which makes the barrier to the rotation of the ammonia ligands not constant but fluctuating. The phase polymorphism and the dynamics of the molecular reorientations of the title compound are similar but not quite identical with these of the [Ni(NH₃)₆](ClO₄)₂.     

Synthesis and characterization of the [Cu(Cin2bda)2]ClO4 and [Cu(Ncin2bda)2]ClO4 complexes: Crystal structure of [Cu(Ncin2bda)2]ClO4

Two copper(I) complexes [Cu(Cin₂bda)₂]ClO₄ (I) and [Cu(Ncin₂bda)₂]ClO₄ (II) have been prepared by the reaction of the ligands N²,N²′-bis(3-phenylallylidene)biphenyl-2,2′-diamine (L¹) and N²,N²′-bis[3-(2-nitrophenyl)allylidene]biphenyl-2,2′-diamine (L²) and copper(I) salt. These compounds were characterized by CHN analyses, ¹H NMR, IR, and UV-Vis spectroscopy. The C=N stretching frequency in the copper(I) complexes shows a shift to a lower frequency relative to the free ligand due to the coordination of the nitrogen atoms. The crystal and molecular structure of II was determined by X-ray single-crystal crystallography. The coordination polyhedron about the copper(I) center in the complex is best described as a distorted tetrahedron. A quasireversible redox behavior was observed for complexes I and II. The article is published in the original.     

Protonation of the acyclic tetraaza metallocomplex of gold(III) [Au(C9H19N4)]2+ in aqueous solution. Synthesis and crystal and molecular structure of [Au(C9H20N4)](H5O2)(ClO4)4

Protonation equilibrium has been studied for the acyclic gold(III) tetraaza metallocomplex [AuB]²⁺ [B = N, N′-bis(2-aminoethyl)-2,4-pentanediiminato(1−)] in aqueous solution. The synthetic procedure is described. The crystal and molecular structure of the protonated form of the [AuHB](H₅O₂)(ClO₄)₄ complex has been determined. Monoclinic crystals with unit cell dimensions a = 11.964(2) Å, b = 13.789(3) Å, c = 15.496(3) Å, β = 109.00(3)°, V = 2417.1(8) ų, Z = 4, ρcalc = 2.243 g/cm³, space group P2₁/n. The structure is built of nearly planar [Au(C₉H₂₀N₄)]³⁺ complex cations, (H₅O₂)⁺ cations, and [ClO₄]⁻ anions. The gold atom coordinates four nitrogen atoms of the ligand, forming a square plane. The six-membered chelate ring of the ligand is protonated at the central β-carbon atom and contains imine C=N bonds. The oxygen atoms of the perchlorate ions are hydrogen bonded to the (H₅O₂)⁺ dihydroxonium ion and to the nitrogen atoms of the NH₂ groups of the [AuHB]³⁺ cation. Original Russian Text Copyright ? 2005 by V. A. Afanasieva, L. A. Glinskaya, R. F. Klevtsova, and I. V. Mironov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 5, pp. 909–915, September–October, 2005.     

[Ag(NH3)2]Ag(OsO3N)2: a new nitridoosmate(VIII)

Dark brown single crystals of [Ag(NH₃)₂]Ag(OsO₃N)₂ were obtained from the reaction of Ag₂CO₃, OsO₄, and NH₃ in aqueous solution. The crystal structure was solved in the monoclinic space group C2/m, with the following unit-cell dimensions: a=1962.5(3), b=633.1(1), c=812.6(1) pm, β=96.71(1)°. The final reliability factor was R=0.0256 for 1034 reflections with I>2σ(I). Linear [Ag(NH₃)₂]⁺ ions are present oriented perpendicular to the [010] direction, leading to short Ag⁺-Ag⁺ distances of 316 pm. A second type of Ag⁺ ions in the crystal structure present coordination number “6+1” and are surrounded by oxygen and nitrogen atoms of the nitridoosmate groups. Within the first of the two crystallographically distinguishable anions one can clearly differentiate between oxygen and nitrogen atoms while the second one exhibits a N/O disorder over two positions. The infrared spectrum of [Ag(NH₃)₂]Ag(OsO₃N)₂ shows the typical absorptions which can be attributed to the complex anions and the NH₃ ligands.     

Syntheses, crystal structures and Raman spectra of Ba(BF4)(PF6), Ba(BF4)(AsF6) and Ba2(BF4)2(AsF6)(H3F4); the first examples of metal salts containing simultaneously tetrahedral BF4 and octahedral AF6 anions

In the system BaF₂/BF₃/PF₅/anhydrous hydrogen fluoride (aHF) a compound Ba(BF₄)(PF₆) was isolated and characterized by Raman spectroscopy and X-ray diffraction on the single crystal. Ba(BF₄)(PF₆) crystallizes in a hexagonal space group with a=10.2251(4) Å, c=6.1535(4) Å, V=557.17(5) Å³ at 200 K, and Z=3. Both crystallographically independent Ba atoms possess coordination polyhedra in the shape of tri-capped trigonal prisms, which include F atoms from BF₄⁻ and PF₆⁻ anions. In the analogous system with AsF₅ instead of PF₅ the compound Ba(BF₄)(AsF₆) was isolated and characterized. It crystallizes in an orthorhombic Pnma space group with a=10.415(2) Å, b=6.325(3) Å, c=11.8297(17) Å, V=779.3(4) Å³ at 200 K, and Z=4. The coordination around Ba atom is in the shape of slightly distorted tri-capped trigonal prism which includes five F atoms from AsF₆⁻ and four F atoms from BF₄⁻ anions. When the system BaF₂/BF₃/AsF₅/aHF is made basic with an extra addition of BaF₂, the compound Ba₂(BF₄)₂(AsF₆)(H₃F₄) was obtained. It crystallizes in a hexagonal P6₃/mmc space group with a=6.8709(9) Å, c=17.327(8) Å, V=708.4(4) Å³ at 200 K, and Z=2. The barium environment in the shape of tetra-capped distorted trigonal prism involves 10 F atoms from four BF₄⁻, three AsF₆⁻ and three H₃F₄⁻ anions. All F atoms, except the central atom in H₃F₄ moiety, act as μ₂-bridges yielding a complex 3-D structural network.     

Calorimetric study and thermal analysis of [Gd4/3Y2/3(Gly)6(H2O)4](ClO4)6·5H2O and [ErY(Gly)6(H2O)4](ClO4)6·5H2O (Gly: glycin)

Two solid-state coordination compounds of rare earth metals with glycin, [Gd_4/3Y_2/3(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O and [ErY(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O were synthesized. The low-temperature heat capacities of the two coordination compounds were measured with an adiabatic calorimeter over the temperature range from 78 to 376 K. [Gd_4/3Y_2/3(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O melted at 342.90 K, while [ErY(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O melted at 328.79 K. The molar enthalpy and entropy of fusion for the two coordination compounds were determined to be 18.48 kJ mol⁻¹ and 53.9 J K⁻¹ mol⁻¹ for [Gd_4/3Y_2/3(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O, 1.82 kJ mol⁻¹ and 5.5 J K⁻¹ mol⁻¹ for [ErY(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O, respectively. Thermal decompositions of the two coordination compounds were studied through the thermogravimetry (TG). Possible mechanisms of the decompositions are discussed.     

Low-dimensional compounds containing cyano groups. XVII. Crystal structure, spectroscopic, thermal and magnetic properties of [Cu(bmen)2][Pt(CN)4] (bmen=N,N′-dimethylethylenediamine)

The synthesis, structural analysis, spectroscopic studies, susceptibility and specific-heat measurements of {[Cu(bmen)₂][Pt(CN)₄]}_n (bmen=N,N′-dimethylethylenediamine) are presented. X-ray crystal-structure analysis revealed that the [Pt(CN)₄]²⁻ building blocks are combined with [Cu(bmen)₂]²⁺ units to form a chain-like structure along the a axis. The Cu(II) atoms are hexacoordinated by four nitrogen atoms in the equatorial plane belonging to two molecules of bidentate bmen ligands with average Cu-N distance of 2.043(18) Å. The axial positions are occupied by two nitrogen atoms from bridging [Pt(CN)₄]²⁻ anions at a longer axial Cu-N distance of 2.490(4) Å. The compound is characterized by the presence of a weak antiferromagnetic exchange coupling J/k_B=0.6 K. Despite the one-dimensional (1D) character of the structure, the analysis of the magnetic properties and specific heat at very low temperatures shows that [Cu(bmen)₂][Pt(CN)₄] behaves as a two-dimensional (2D) square-lattice Heisenberg magnet with weak interlayer coupling.     

New open-framework in the uranyl vanadates A3(UO2)7(VO4)5O (A=Li, Ag) with intergrowth structure between A(UO2)4(VO4)3 and A2(UO2)3(VO4)2O

New uranyl vanadates A₃(UO₂)₇(VO₄)₅O (M=Li (1), Na (2), Ag (3)) have been synthesized by solid-state reaction and their structures determined from single-crystal X-ray diffraction data for 1 and 3. The tetragonal structure results of an alternation of two types of sheets denoted S for _∞²[UO₂(VO₄)₂]⁴⁻ and D for _∞²[(UO₂)₂(VO₄)₃]⁵⁻ built from UO₆ square bipyramids and connected through VO₄ tetrahedra to _∞¹[U(3)O₅-U(4)O₅]⁸⁻ infinite chains of edge-shared U(3)O₇ and U(4)O₇ pentagonal bipyramids alternatively parallel to a- and b-axis to construct a three-dimensional uranyl vanadate arrangement. It is noticeable that similar _∞[UO₅]⁴⁻ chains are connected only by S-type sheets in A₂(UO₂)₃(VO₄)₂O and by D-type sheets in A(UO₂)₄(VO₄)₃, thus A₃(UO₂)₇(VO₄)₅O appears as an intergrowth structure between the two previously reported series. The mobility of the monovalent ion in the mutually perpendicular channels created in the three-dimensional arrangement is correlated to the occupation rate of the sites and by the geometry of the different sites occupied by either Na, Ag or Li. Crystallographic data: 293 K, Bruker X8-APEX2 X-ray diffractometer equipped with a 4 K CCD detector, MoKα, λ=0.71073 Å, tetragonal symmetry, space group P4¯m2, Z=1, full-matrix least-squares refinement on the basis of F²; 1,a=7.2794(9) Å, c=14.514(4) Å, R1=0.021 and wR2=0.048 for 62 parameters with 782 independent reflections with I?2σ(I); 3, a=7.2373(3) Å, c=14.7973(15) Å, R1=0.041 and wR2=0.085 for 60 parameters with 1066 independent reflections with I?2σ(I).     

Synthesis,Characterization, and DNA Binding Properties of Dinuclear Copper（Ⅱ） Complex [Cu2（TATP）2（L-Leu）2（CIO4）2]2·2H2O

A dinuclear copper（Ⅱ） complex[Cu2（TATP）2（L-Leu）2（CIO4）2]2·2H2Owas synthesized and characterized, where, TATP=1,4,8,9-tetraazatriphenylene, and L-Leu=L-leucinate. The complex was crystallized in the triclinic space group P1, with two independent molecules in a unit cell. Two Cu（Ⅱ） ions in each complex [Cu2（TATP）2（L-Leu）2（CIO4）2] molecule were found to be in different coordination geometries, i.e., Cu2 or Cu4 of a distorted square-pyramidal geometry coordinated with two nitrogens of TATP, the amino nitrogen and one carboxylate oxygen of L-Leu and one oxygen of perchlorate, and Cul or Cu3 with an octahedral geometry coordinated with the above stated similar coordinated atoms, and another carboxylate oxygen of L-Leu coordinating to Cu2 or Cu4. The complex can interact with CT-DNA by an intercalative mode and cleave pBR322 DNA in the presence of ascorbate.     

Single crystal structure and Raman spectrum of Ba3Na2(CN2)4

The synthesis, single crystal structure determination, and Raman spectrum are reported for colorless transparent tribarium disodium tetracyanamide, Ba₃Na₂(CN₂)₄. The title compound crystallizes in the space group C_2h⁵-P2₁/c (#14, , , , β=110.454(4)°, , Z=4, R/wR=0.0266/0.0543). Each sodium atom is surrounded by six nitrogen atoms in octahedral geometry. Sodium centered nitrogen octahedra are linked through face-sharing along the [100] direction to form one-dimensional (1D) chains. These chains are connected to each other through the carbon atoms of cyanamide and make a three-dimensional (3D) network with 1D channels along the [100] direction. Barium atoms and additional cyanamide anions reside in the channels. Each barium atom is irregularly coordinated with nitrogen and carbon from the cyanamide anions. The Raman spectrum shows symmetric vibrations of [NCN]²⁻ corresponding to ν_sym (1241.5 cm⁻¹) and 2δ (1356.4 cm⁻¹).     

Hydrothermal Synthesis, Single-Crystal Structure Analysis, and Solid-State NMR Characterization of Zn2(OH)0.14(3)F0.86(3)(PO4)

The zinc fluoro phosphate Zn₂F(PO₄) has been produced by hydrothermal synthesis employing hydrofluoric acid as a mineralizer in a H₂O or D₂O medium. A single-crystal X-ray synchrotron diffraction analysis of Zn₂F(PO₄) shows that the zinc fluoro phosphate is monoclinic, a=9.690(1), b=12.793(1), and c=11.972(1) Å, β=108.265(1)°, space group P2₁/c, No. 14, Z=16. Reflections hkl with k=2n+1 are weak but significant and the structure shows pseudosymmetry. Zn₂F(PO₄) has the wagnerite-type M₂F(XO₄) structure with four Zn atoms each coordinated to four O atoms and one F atom while four other Zn atoms are coordinated to four O atoms and two F atoms. A difference Fourier map, calculated from the single-crystal X-ray data, shows additional electron density close to the four fluorine atoms, indicating a possible partial substitution of F⁻ by OH⁻ ions. This is unambiguously confirmed by ³¹P-{¹H} cross-polarization magic-angle spinning (MAS) and by ¹H/²H MAS NMR spectroscopy. The narrow line width observed for the ¹H resonance and the unique set of ²H quadrupole coupling parameters (obtained for the Zn₂F(PO₄) sample using D₂O as medium) show that ¹H/²H is present as OH(D) groups rather than as water of crystallization in the structure. Quantitative ¹H MAS NMR analysis shows that the composition of the sample is Zn₂(OH)_0.14(3)F_0.86(3)(PO₄). The high-speed ¹⁹F MAS NMR spectrum exhibits two resolved resonances with equal intensity, which are ascribed to an overlap of resonances from the four distinct fluorine sites in Zn₂(OH)_0.14(3)F_0.86(3)(PO₄).     

Hydro(solvo)thermal synthesis and structural characterization of a new organically templated gallophosphate: [H3N(CH2)2NH3]1/2·[Ga5 (PO4)4(OH)4]

A new three-dimensional open-framework gallophosphate: [H₃N(CH₂)₂NH₃]_1/2·[Ga₅ (PO₄)₄(OH)₄] has been prepared by hydro(solvo)thermal synthesis in presence of ethylenediamine (en) as structure-directing agent. Its structure was determined by means of single-crystal X-ray diffraction analysis with the following crystal data: monoclinic space group C2/m, a=10.1604(9) Å, b=12.0085(15) Å, c=7.1892(7) Å, β=90.797(6)°, V=877.08(16) Å³, Z=2, R₁=0.0264, wR₂=0.0764. The total numbers of measured reflections and unique reflections were 3508 and 1300, respectively. It is built up from a new secondary building unit (SBU) Ga₄P₄O₂₀(OH)₄, in which Ga atoms exhibit distorted trigonal bipyramidal coordination and P atoms are in tetrahedral coordination. The SBU Ga₄P₄O₂₀(OH)₄ are linked into a layer by bridge oxygen atoms. The GaO₄(OH)₂ octahedra link the layers into a three-dimentional framework. Diprotonated ethylenediamine was found in the channel of the framework. The material was characterized by IR spectroscopy, ¹H NMR spectra, thermogravimetric and differential thermal analyses and elemental analysis.     

Structure of Ba Na Ethylenediaminetetraacetatocobaltate(III) Perchlorate, Na[Ba6(H2O)25][Co(Edta)]4(ClO4)9 · 5H2O

Crystals with uncommon composition NaBa₆[Co(Edta)]₄(ClO₄)₉ · 30H₂O (Edta⁴⁻ is ethylenediaminetetraacetic acid anion) were obtained with the following unit cell parameters: a = 14.8513(9) Å, b = 26.2361(15) Å, c = 15.1789(9) Å, α = 91.661(7)°, β = 113.035(7)°, γ = 89.897(7)°, space group P1¯. Each complex anion [Co(Edta)]⁻ is bonded through the carboxyl O atoms to five Ba atoms to give three-dimensional framework in a crystal. One perchlorate ion forms Ba-O-Cl-O-Ba bridge between the Ba atoms; four ClO ₄ ⁻ ions are isolated, while the remaining four ions act as monodentate ligands at the Ba atoms. The water molecules (25 in sum) complete the coordination sphere of the Ba atoms to eight-, nine-, or ten-vertex polyhedron. Four water molecules are in the closest surrounding of the Na atom, one H₂O molecule is isolated.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 8, 2005, pp. 590–595.Original Russian Text Copyright © 2005 by Zabel, Poznyak, Pawlowski.     

Hydrothermal Synthesis and Crystal Structure of the First Ammonium Indium(III) Phosphate NH4In(OH)PO4 with Spiral Chains of InO4(OH)2

An ammonium indium hydrogen phosphate, NH₄In(OH)PO₄, was synthesized under mild hydrothermal conditions, and the crystal structure was characterized by single-crystal X-ray diffraction method. The compound crystallizes with the RbIn(OH)PO₄ type with the following data: M_r=244.84, tetragonal, tP104, P4₃2₁2 (No.96), a=9.416(2) Å, c=11.159(3) Å, V=989.9(3) ų, Z=8, D_x=3.288 g cm⁻³, λ=0.71073 Å, μ=50.34 cm⁻¹, F(000)=928, T=293 K, R1=0.0606, wR2=0.1472 for 91 variables and 1813 contributing unique reflections. The structure is characterized by chiral InO₄(OH)₂ chains along the c axis formed by sharing OH corners. The chains are isolated by PO₄ tetrahedra leading to a three-dimensional framework structure with channels occupied by NH₄⁺ ions. The framework structure is similar to that of KIn(OH)PO₄ and γ-NaTiOPO₄. The hydrogen bonds formed by NH₄⁺ with the polyhedral oxygen atoms play an important role in the anisotropic changes of the lattice with respect to its alkali metal analogues. The topological construction of the title structure can be considered as an augmented 4,6-net with larger porosity.     

Crystal Structures and Magnetic Properties of the Two Misfit Layer Compounds: [SrGd0.5S1.5]1.16 NbS2 and [Sr(Fe,Nb)0.5S1.5]1.13 NbS2

Crystal structures of two new misfit compounds, [SrGd_0.5S_1.5]_1.16NbS₂ and [Sr(Fe,Nb)_0.5S_1.5]_1.13NbS₂, were determined through the composite approach, i.e., by refining each subpart (Q, H-parts, and the common part) of these composite materials, separately. The Q-part is a three-atom-thick layer, with the NaCl-type structure, where external SrS planes enclose the inner GdS or (Fe,Nb)S plane; the structural difference between these two compounds lies in the central layer within the Q-part: Gd and S atoms are in special positions (octahedral coordination), while Fe and S atoms are statistically distributed on split (×4) positions (tetrahedral coordination) around a central unique site (=special position occupied by Nb). The H-part is a sandwich of sulfur planes enclosing the inner Nb plane as observed for the structure of the binary compound NbS₂ itself. The Sr-Gd derivative shows a paramagnetic behavior in the whole studied temperature range (2-300 K). On the other hand, antiferromagnetic interactions occur in the Sr-Fe derivative; the complex magnetic behavior of this compound is related to the statistical distribution of Fe atoms which leads to frustration of the magnetic interactions. At room temperature, experimental values obtained from Mössbauer spectrum correspond to Fe³⁺ in tetrahedral sulfur environment: isomer shift δ=0.32 mm s⁻¹, and quadrupole splitting ΔE=0.48 mm s⁻¹.     

Synthesis, vibrational and NMR spectroscopic characterization of [N(CH3)4][IO2F2] and X-ray crystal structure of [N(CH3)4]2[IO2F2][HF2]

The salt, [N(CH₃)₄][IO₂F₂], was prepared from [N(CH₃)₄][IO₃] and 49% aqueous HF, and characterized by Raman, infrared, and ¹⁹F NMR spectroscopy. Crystals of [N(CH₃)₄]₂[IO₂F₂][HF₂] were obtained by reduction of [N(CH₃)₄][cis-IO₂F₄] in the presence of [N(CH₃)₄][F] in CH₃CN solvent and were characterized by Raman spectroscopy and single-crystal X-ray diffraction: C2/m, a = 14.6765(2) Å, b = 8.60490(10) Å, c = 13.9572(2) Å, β = 120.2040(10)°, V = 1523.35(3) Å³, Z = 4 and R = 0.0192 at 210 K. The crystal structure consists of two IO₂⁻F₂ anions that are symmetrically bridged by two H⁻F₂ anions, forming a [F₂O₂I(FHF)₂IO₂F₂]⁴⁻ dimer. The symmetric bridging coordination for the H⁻F₂ anion in this structure represents a new bonding modality for the bifluoride anion.     

New Molybdenyl Iodates: Hydrothermal Preparation and Structures of Molecular K2MoO2(IO3)4 and Two-Dimensional β-KMoO3(IO3)

Two new molybdenyl iodates, K₂MoO₂(IO₃)₄ (1) and β-KMoO₃(IO₃) (2), have been prepared from the reactions of MoO₃ with KIO₄ and NH₄Cl at 180°C in aqueous media. The structure of 1 consists of molecular [MoO₂(IO₃)₄]²⁻ anions separated by K⁺ cations. The Mo(VI) centers are ligated by two cis-oxo ligands and four monodentate iodate anions. Both terminal and bridging oxygen atoms of the iodate anions form long ionic contacts with the K⁺ cations. β-KMoO₃(IO₃) (2) displays a two-dimensional layered structure constructed from ²_∞[(MoO₃(IO₃)]¹⁻ anionic sheets separated by K⁺ cations. These sheets are built from one-dimensional chains formed from corner-sharing MoO₆ octahedra that run along the b-axis that are linked together through bridging iodate groups. K⁺ cations separate the layers from one another and form long contacts with oxygen atoms from both the iodate anions and molybdenyl moieties. Crystallographic data: 1, monoclinic, space group C2/c, a=12.8973(9) Å, b=6.0587(4) Å, c=17.694(1) Å, β=102.451(1)°, Z=4, MoKα, λ=0.71073, R(F)=2.64% for 97 parameters with 1584 reflections with I>2σ(I); 2, monoclinic, space group P2₁/n, a=7.4999(6) Å, b=7.4737(6) Å, c=10.5269(8) Å, β=109.023(1)°, Z=4, MoKα, λ=0.71073, R(F)=2.73% for 83 parameters with 1334 reflections with I>2σ(I).