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1.
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) Å3, 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. 相似文献
2.
Stanislav Filatov Yurij Shepelev Natalia Sennova Yury F. Kargin 《Journal of solid state chemistry》2004,177(2):515-522
The paper presents a new data on the crystal structure, thermal expansion and IR spectra of Bi3B5O12. The Bi3B5O12 single crystals were grown from the melt of the same stoichiometry by Czochralski technique. The crystal structure of Bi3B5O12 was refined in anisotropic approximation using single-crystal X-ray diffraction data. It is orthorhombic, Pnma, a=6.530(4), b=7.726(5), c=18.578(5) Å, V=937.2(5) Å3, Z=4, R=3.45%. Bi3+ atoms have irregular coordination polyhedra, Bi(1)O6 (d(B-O)=2.09-2.75 Å) and Bi(2)O7 (d(B-O)=2.108-2.804 Å). Taking into account the shortest bonds only, these polyhedra are considered here as trigonal Bi(1)O3 (2.09-2.20 Å) and tetragonal Bi(2)O4 (2.108-2.331 Å) irregular pyramids with Bi atoms in the tops of both pyramids. The BiO4 polyhedra form zigzag chains along b-axis. These chains alternate with isolated anions [B2IVB3IIIO11]7− through the common oxygen atoms to form thick layers extended in ab plane. A perfect cleavage of the compound corresponds to these layers and an imperfect one is parallel to the Bi-O chains. The Bi3B5O12 thermal expansion is sharply anisotropic (α11≈α22=12, α33=3×10−6 °C−1) likely due to a straightening of the flexible zigzag chains along b-axis and decreasing of their zigzag along c-axis. Thus the properties like cleavage and thermal expansion correlate to these chains. 相似文献
3.
S. Shenawi-KhalilV. Uvarov D.O. Charkin A. GoazI. Popov V.A. DolgikhY. Sasson 《Solid State Sciences》2012,14(1):159-165
We report here the first observation of a bismuth potassium nitrate Bi1.7K0.9O2(NO3)2, obtained via thermal decomposition of bismuth and potassium nitrate mixtures. The new compound is orthorhombic, space group Immm (71), Z = 2, with a = 3.8698(7) Å, b = 3.8703(7) Å, and c = 24.1271(4) Å. Its crystal structure was refined from powder X-ray diffraction data by analogy with the mineral beyerite, Bi2O2Ca(CO3)2. The morphology and elemental composition of Bi1.7K0.9O2(NO3)2 were characterized using scanning electron microscopy (SEM) with energy dispersive X-Ray spectroscopy (EDS). Its phase transformations upon heating and products of its thermal decomposition were studied using XRD, TGA and FTIR. At 440 °C, Bi1.7K0.9O2(NO3)2 transforms to another basic bismuth potassium nitrate with demonstrates a very similar XRD pattern but slightly larger cell parameters. At 520 °C, the intermediate oxide nitrate decomposes into a mixture of crystalline α-Bi2O3 and KNO3. The as prepared Bi1.7K0.9O2(NO3)2 showed lower than TiO2 (Degussa P25) photocatalytic activity upon decomposition of a widely used model pollutant, Rhodamine B (RhB) and photooxidation of potassium iodide under UV-vis light irradiation. Interaction with potassium iodide in alkaline media resulted in formation of Bi5O7I. 相似文献
4.
Tom Baikie Zahara Ahmad Antoine Maignan T.J. White 《Journal of solid state chemistry》2007,180(5):1538-1546
Solid-state reaction between SrCO3, Cr2O3 and SrF2 has produced the apatite phase Sr10(CrO4)6F2 and Sr2CrO4 which adopts the K2NiF4-type structure. The reaction outcome was very sensitive to the heating rate with rapid rise times favouring the formation of Sr2CrO4, which has been synthesised at ambient pressure for the first time. Powder X-ray diffraction and electron diffraction confirmed that Sr2CrO4 adopts a body centred tetragonal cell (space group I4/mmm) with lattice parameters a=3.8357(1) Å and c=12.7169(1) Å, while a combination of neutron and X-ray diffraction verified Sr10(CrO4)6F2 is hexagonal (space group P63/m) with lattice parameters a=9.9570(1) Å and c=7.4292(1) Å. X-ray photoelectron spectroscopy and magnetic measurements were used to characterise the oxidation states of chromium contained within these phases. 相似文献
5.
Shilie Pan Jared P. Smit Evan S. Stampler Jaewook Baek Kenneth R. Poeppelmeier 《Journal of solid state chemistry》2008,181(8):2087-2091
Bi2Cu5B4O14 crystallizes in the noncentrosymmetric triclinic space group P1 (No. 1) with cell parameters a=10.1381(11) Å, b=9.3917(11) Å, c=3.4566(4) Å, α=105.570(2)°, β=92.275(2)°, γ=107.783(2)°, Z=1 and R1=0.0401 and wR2=0.0980. It is a layered structure that is built up from sheets of rectangular CuO4 and trigonal BO3 groups. The sheets are connected by infinite chains of edge shared BiO6 polyhedra that intersect the bc plane at an angle slightly greater than 90°. The second-harmonic generation efficiency of Bi2Cu5B4O14, using 1064 nm radiation, is about one half times that of KH2PO4. 相似文献
6.
Digamber G. Porob 《Journal of solid state chemistry》2004,177(12):4535-4541
Two new compounds Ca0.5Bi3V2O10 and Sr0.5Bi3V2O10 have been synthesized in the ternary system: MO-Bi2O3-V2O5 system (M=M2+). The crystal structure of Sr0.5Bi3V2O10 has been determined from single crystal X-ray diffraction data, space group and Z=2, with cell parameters a=7.1453(3) Å, b=7.8921(3) Å, c=9.3297(3) Å, α=106.444(2)°, β=94.088(2)°, γ=112.445(2)°, V=456.72(4) Å3. Ca0.5Bi3V2O10 is isostructural with Sr0.5Bi3V2O10, with, a=7.0810(2) Å, b=7.8447(2) Å, c=9.3607(2) Å, α=106.202(1)°, β=94.572(1)°, γ=112.659(1)°, V=450.38(2) Å3 and its structure has been refined by Rietveld method using powder X-ray data. The crystal structure consists of infinite chains of (Bi2O2) along c-axis formed by linkage of BiO8 and BiO6 polyhedra interconnected by MO8 polyhedra forming 2D layers in ac plane. The vanadate tetrahedra are sandwiched between these layers. Conductivity measurements give a maximum conductivity value of 4.54×10−5 and 3.63×10−5 S cm−1 for Ca0.5Bi3V2O10 and Sr0.5Bi3V2O10, respectively at 725 °C. 相似文献
7.
8.
Magnus G. Johnston 《Journal of solid state chemistry》2004,177(12):4680-4686
The hydrothermal syntheses, single crystal structures, and some properties of Ba2MnIIMn2III(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 SeIV lone pairs. Crystal data: Ba2Mn3(SeO3)6, Mr=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, Mr=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. 相似文献
9.
Richard E. Sykora Brian L. Scott Thomas E. Albrecht-Schmitt 《Journal of solid state chemistry》2004,177(3):725-730
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). 相似文献
10.
Single crystals of the oxidephosphates TiIIITiIV3O3(PO4)3 (black), CrIII4TiIV27O24(PO4)24 (red-brown, transparent), and FeIII4TiIV27O24(PO4)24 (brown) with edge-lengths up to 0.3 mm were grown by chemical vapour transport. The crystal structures of these orthorhombic members (space group F2dd ) of the lazulite/lipscombite structure family were refined from single-crystal data [TiIIITiIV3O3(PO4)3: Z=24, a=7.3261(9) Å, b=22.166(5) Å, c=39.239(8) Å, R1=0.029, wR2=0.084, 6055 independent reflections, 301 variables; CrIII4TiIV27O24(PO4)24: Z=1, a=7.419(3) Å, b=21.640(5) Å, c=13.057(4) Å, R1=0.037, wR2=0.097, 1524 independent reflections, 111 variables; FeIII4TiIV27O24(PO4)24: Z=1, a=7.4001(9) Å, b=21.7503(2) Å, c=12.775(3) Å, R1=0.049, wR2=0.140, 1240 independent reflections, 112 variables). For TiIIITiIVO3(PO4)3 a well-ordered structure built from dimers [TiIII,IV2O9] and [TiIV,IV2O9] and phosphate tetrahedra is found. The metal sites in the crystal structures of Cr4Ti27O24(PO4)24 and Fe4Ti27O24(PO4)24, consisting of dimers [MIIITiIVO9] and [TiIV,IV2O9], monomeric [TiIVO6] octahedra, and phosphate tetrahedra, are heavily disordered. Site disorder, leading to partial occupancy of all octahedral voids of the parent lipscombite/lazulite structure, as well as splitting of the metal positions is observed. According to Guinier photographs TiIII4TiIV27O24(PO4)24 (a=7.418(2) Å, b=21.933(6) Å, c=12.948(7) Å) is isotypic to the oxidephosphates MIII4TiIV27O24(PO4)24 (MIII: Cr, Fe). The UV/vis spectrum of Cr4Ti27O24(PO4)24 reveals a rather small ligand-field splitting Δo=14,370 cm−1 and a very low nephelauxetic ratio β=0.72 for the chromophores [CrIIIO6] within the dimers [CrIIITiIVO9]. 相似文献
11.
Two new potassium uranyl molybdates K2(UO2)2(MoO4)O2 and K8(UO2)8(MoO5)3O6 have been obtained by solid state chemistry . The crystal structures were determined by single crystal X-ray diffraction data, collected with MoKα radiation and a charge coupled device (CCD) detector. Their structures were solved using direct methods and Fourier difference techniques and refined by a least square method on the basis of F2 for all unique reflections, with R1=0.046 for 136 parameters and 1412 reflections with I?2σ(I) for K2(UO2)2(MoO4)O2 and R1=0.055 for 257 parameters and 2585 reflections with I?2σ(I) for K8(UO2)8(MoO5)3O6. The first compound crystallizes in the monoclinic symmetry, space group P21/c with a=8.250(1) Å, b=15.337(2) Å, c=8.351(1) Å, β=104.75(1)°, ρmes=5.22(2) g/cm3, ρcal=5.27(2) g/cm3 and Z=4. The second material adopts a tetragonal unit cell with a=b=23.488(3) Å, c=6.7857(11) Å, ρmes=5.44(3) g/cm3, ρcal=5.49(2) g/cm3, Z=4 and space group P4/n.In both structures, the uranium atoms adopt a UO7 pentagonal bipyramid environment, molybdenum atoms are in a MoO4 tetrahedral environment for K2(UO2)2(MoO4)O2 and MoO5 square pyramid coordination in K8(UO2)8(MoO5)3O6. These compounds are characterized by layered structures. The association of uranyl ions (UO7) and molybdate oxoanions MoO4 or MoO5, give infinite layers [(UO2)2(MoO4)O2]2− and [(UO2)8(MoO5)3O6]8− in K2(UO2)2(MoO4)O2 and K8(UO2)8(MoO5)3O6, respectively. Conductivity properties of alkali metal within the interlayer spaces have been measured and show an Arrhenius type evolution. 相似文献
12.
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. 相似文献
13.
Powder samples of the Cr6+-containing compound Bi6Cr2O15 were prepared by solid state reaction of Bi2O3 and Cr2O3 in air at 650°C. The structure was solved and refined using high-resolution neutron powder diffraction data in space group Ccc2, with anisotropic thermal displacement parameters a=12.30184(5), b=19.87492(7), and c=5.88162(2) Å, V=1438.0 Å3, and 126 variables to RF=1.8%. Bi6Cr2O15 exhibits a new structure type that contains (Bi12O14)8n+n columns, of the kind previously found only for phases isotypic with Bi13Mo4VO34. Each column is surrounded by eight CrO2−4 tetrahedra. The ionic conductivity of Bi6Cr2O15 was determined by impedance measurements to be 3.5×10−5 (Ω cm)−1 at 600°C. 相似文献
14.
Besma Bouzemi Friaa 《Journal of solid state chemistry》2003,173(2):273-279
The potassium chromium (III) arsenate K3Cr3(AsO4)4 is prepared by solid state reaction at 900°C from a mixture of K2CO3, As2O3 and (NH4)2Cr2O7. It is structurally characterized by single-crystal X-ray diffraction. It crystallizes in the Cmca (no. 64) space group with a=10.671(1) Å, b=20.911(5) Å, c=6.500(3) Å, V=1450.4(8) Å3, Z=4, R(F2)=0.0424 and Rω(F2)=0.1199 for 846 reflections with F2>2σ(F2). The structure consists of CrO6 octahedra and AsO4 tetrahedra sharing corners and edges to form a two-dimensional framework. The K+(2) cations are located in the interlayer space. Conductivity measurement () shows that K3Cr3(AsO4)4 is a poor ionic conductor. 相似文献
15.
Xuean Chen Yinghua Zhao Jianlong Zuo Weiqiang Xiao 《Journal of solid state chemistry》2006,179(12):3911-3918
Two new hydrated borates, Zn8[(BO3)3O2(OH)3] and Pb[B5O8(OH)]·1.5H2O, have been prepared by hydrothermal reactions at 170 °C. Single-crystal X-ray structural analyses showed that Zn8[(BO3)3O2(OH)3] crystallizes in a non-centrosymmetric space group R32 with a=8.006(2) Å, c=17.751(2) Å, Z=3 and Pb[B5O8(OH)]·1.5H2O in a triclinic space group P1¯ with a=6.656(2) Å, b=6.714(2) Å, c=10.701(2) Å, α=99.07(2)°, β=93.67(2)°, γ=118.87(1)°, Z=2. Zn8[(BO3)3O2(OH)3] represents a new structure type in which Zn-centered tetrahedra are connected via common vertices leading to helical ribbons ∞1[Zn8O15(OH)3]17− that pack side by side and are further condensed through sharing oxygen atoms to form a three-dimensional ∞3[Zn8O11(OH)3]9− framework. The boron atoms are incorporated into the channels in the framework to complete the final structure. Pb[B5O8(OH)]·1.5H2O is a layered compound containing double ring [B5O8(OH)]2− building units that share exocyclic oxygen atoms to form a two-dimensional layer. Symmetry-center-related layers are stacked along the c-axis and held together by interlayer Pb2+ ions and water molecules via electrostatic and hydrogen bonding interactions. The IR spectra further confirmed the existence of both triangular BO3 and OH groups in Zn8[(BO3)3O2(OH)3], and BO3, BO4, OH groups as well as guest water molecules in Pb[B5O8(OH)]·1.5H2O. 相似文献
16.
Bi5AgNb4O18 is a new phase, which was discovered during the phase equilibrium study of the Bi2O3-Ag2O-Nb2O5 system. Bi5AgNb4O18 was prepared at 750°C and is stable in air up to its melting temperature of 1160.1±5.0°C (standard error of estimate). Results of a Rietveld refinement using neutron powder diffraction confirmed that Bi5AgNb4O18 is isostructural with Bi3TiNbO9, Bi5NaNb4O18, and Bi5KNb4O18. The structure was refined in the orthorhombic space group A21am, Z=2, and the lattice parameters are a=5.4915(2) Å, b=5.4752(2) Å, c=24.9282(8) Å, and V=749.52(4) Å3. The structure can be described as the m=2 member of the Aurivillius family, (Bi2O2)2+ (Am−1BmO3m+1)2− (where A=Bi and B=Ag, Nb), which is characterized by perovskite-like (Am−1BmO3m+1)2− slabs regularly interleaved with (Bi2O2)2+ layers. The octahedral [NbO6] units are distorted with Nb-O distances ranging from 1.856(4) to 2.161(2) Å and the O-Nb-O angles ranging from 82.6(3)° to 98.5(3)°. These octahedra are tilted about the a- and c-axis by about 10.3° and 12.4°, respectively. Ag was found to substitute exclusively into the Bi-site that is located in the layer between the two distorted [NbO6] units. Although the Ag substitutes into the Bi-site with the Bi:Ag ratio of 1:1, the existence of a superlattice was not detected using electron diffraction. A comparison of (Bi2O2)2+(Am−1NbmO3m+1)2− structures (where A=Ag, Na, and K) revealed a relation between the pervoskite tolerance factor, t, and structural distortion. The reference pattern for Bi5AgNb4O18 has been submitted to the International Centre for Diffraction Data (ICDD) for inclusion in the Powder Diffraction File. 相似文献
17.
A new layered inorganic-organic hybrid aluminum phosphate-oxalate [H3N(CH2)4NH3]2[Al4(C2O4)(H2PO4)2(PO4)4]·4[H2O](AlPO-CJ25) has been synthesized hydrothermally, by using 1,4-diaminobutane (DAB) as structure-directing agent. The structure has been solved by single-crystal X-ray diffraction analysis and further characterized by IR, 31P MAS NMR, TG-DTA as well as compositional analyses. Crystal data: the triclinic space group P-1, a=8.0484(7) Å, b=8.8608(8) Å, c=13.2224(11) Å, α=80.830(6)°, β=74.965(5)°, γ=78.782(6)°, Z=2, R1[I>2σ(I)]=0.0511 and wR2(all data)=0.1423. The alternation of AlO4 tetrahedra and PO4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO6 octahedra to form the layered structure with 4,6-net sheet. Interestingly, oxalate ions are bis-bidentately bonded by participating in the coordination of AlO6, and bridging the adjacent AlO6 octahedra. The layers are held with each other through strong H-bondings between the terminal oxygens. The organic ammonium cations and water molecules are located in the large cavities between the interlayer regions. 相似文献
18.
A new oxide, Bi14Sr21Fe12O61, with a layered structure derived from the 2212 modulated type structure Bi2Sr3Fe2O9, was isolated. It crystallizes in the I2 space group, with the following parameters: a=16.58(3) Å, b=5.496(1) Å, c=35.27(2) Å and β=90.62°. The single crystal X-ray structure determination, coupled with electron microscopy, shows that this ferrite is the m=5 member of the [Bi2Sr3Fe2O9]m[Bi4Sr6Fe2O16] collapsed family. This new collapsed structure can be described as slices of 2212 structure of five bismuth polyhedra thick along , shifted with respect to each other and interconnected by means of [Bi4Sr6Fe2O16] slices. The latter are the place of numerous defects like iron or strontium for bismuth substitution; they can be correlated to intergrowth defects with other members of the family. 相似文献
19.
The high-temperature polymorphs of two photocatalytic materials, BiNbO4 and BiTaO4 were synthesized by the ceramic method. The crystal structures of these materials were determined by single-crystal X-ray diffraction. BiNbO4 and BiTaO4 crystallize into the triclinic system P1¯ (No. 2), with a=5.5376(4) Å, b=7.6184(3) Å, c=7.9324(36) Å, α=102.565(3)°, β=90.143(2)°, γ=92.788 (4)°, V=326.21 (5) Å3, Z=4 and a=5.931 (1) Å, b=7.672 (2) Å, c=7.786 (2) Å, α=102.94 (3)°, β=90.04 (3)° γ=93.53 (3)°, V=344.59 (1) Å3 and Z=4, respectively. The structures along the c-axis, consist of layers of [Bi2O2] units separated by puckered sheets of (Nb/Ta)O6 octahedra. Photocatalytic studies on the degradation of dyes indicate selectivity of BiNbO4 towards aromatics containing quinonic and azo functional groups. 相似文献
20.
The basic mercury(I) chromate(VI), Hg6Cr2O9 (=2Hg2CrO4·Hg2O), has been obtained under hydrothermal conditions (200 °C, 5 days) in the form of orange needles as a by-product from reacting elemental mercury and K2Cr2O7. Hydrothermal treatment of microcrystalline Hg6Cr2O9 in demineralised water at 200 °C for 3 days led to crystal growth of red crystals of the basic mercury(I, II) chromate(VI), Hg6Cr2O10 (=2Hg2CrO4·2HgO). The crystal structures were solved and refined from single crystal X-ray data sets. Hg6Cr2O9: space group P212121, Z=4, a=7.3573(12), b=8.0336(13), , 3492 structure factors, 109 parameters, R[F2>2σ(F2)]=0.0371, wR(F2 all)=0.0517; Hg6Cr2O10: space group Pca21, Z=4, a=11.4745(15), b=9.4359(12), , 3249 structure factors, 114 parameters, R[F2>2σ(F2)]=0.0398, wR(F2 all)=0.0625. Both crystal structures are made up of an intricate mercury-oxygen network, subdivided into single building blocks [O-Hg-Hg-O] for the mercurous compound, and [O-Hg-Hg-O] and [O-Hg-O] for the mixed-valent compound. Hg6Cr2O9 contains three different Hg22+ dumbbells, whereas Hg6Cr2O10 contains two different Hg22+ dumbbells and two Hg2+ cations. The HgI-HgI distances are characteristic and range between 2.5031(15) and 2.5286(9) Å. All Hg22+ groups exhibit an unsymmetrical oxygen environment. The oxygen coordination of the Hg2+ cations is nearly linear with two tightly bonded O atoms at distances around 2.07 Å. For both structures, the chromate(VI) anions reside in the vacancies of the Hg-O network and deviate only slightly from the ideal tetrahedral geometry with average Cr-O distances of ca. 1.66 Å. Upon heating at temperatures above 385 °C, Hg6Cr2O9 decomposes in a four-step mechanism with Cr2O3 as the end-product at temperatures above 620 °C. 相似文献