Chemistry in Molten Alkali Metal Polyselenophosphate Fluxes. Influence of Flux Composition on Dimensionality. Layers and Chains in APbPSe(4), A(4)Pb(PSe(4))(2) (A = Rb, Cs), and K(4)Eu(PSe(4))(2)

The reaction of Pb and Eu with a molten mixture of A(2)Se/P(2)Se(5)/Se produced the quaternary compounds APbPSe(4), A(4)Pb(PSe(4))(2) (A = Rb,Cs), and K(4)Eu(PSe(4))(2). The red crystals of APbPSe(4) are stable in air and water. The orange crystals of A(4)Pb(PSe(4))(2) and K(4)Eu(PSe(4))(2) disintegrate in water and over a long exposure to air. CsPbPSe(4) crystallizes in the orthorhombic space group Pnma (No. 62) with a = 18.607(4) ?, b = 7.096(4) ?, c = 6.612(4) ?, and Z = 4. Rb(4)Pb(PSe(4))(2) crystallizes in the orthorhombic space group Ibam (No. 72) with a = 19.134(9) ?, b = 9.369(3) ?, c = 10.488(3) ?, and Z = 4. The isomorphous K(4)Eu(PSe(4))(2) has a = 19.020(4) ?, b = 9.131(1) ?, c = 10.198(2) ?, and Z = 4. The APbPSe(4) have a layered structure with [PbPSe(4)](n)()(n)()(-) layers separated by A(+) ions. The coordination geometry around Pb is trigonal prismatic. The layers are composed of chains of edge sharing trigonal prisms running along the b-direction. [PSe(4)](3)(-) tetrahedra link these chains along the c-direction by sharing edges and corners with the trigonal prisms. A(4)M(PSe(4))(2) (M = Pb, Eu) has an one-dimensional structure in which [M(PSe(4))(2)](n)()(n)()(-) chains are separated by A(+) ions. The coordination geometry around M is a distorted dodecahedron. Two [PSe(4)](3)(-) ligands bridge two adjacent metal atoms, using three selenium atoms each, forming in this way a chain along the c-direction. The solid state optical absorption spectra of the compounds are reported. All compounds melt congruently in the 597-620 degrees C region.     

Reactions of Ph4Se4Br4 with tertiary phosphines. Structural isomerism within a series of R3PSe(Ph)Br compounds

The synthesis and characterisation of Ph(4)Se(4)Br(4) (1) directly from the reaction of Ph(2)Se(2) with dibromine is reported. The solid-state structure of 1 consists of four PhSeBr units linked by weak selenium-selenium bonds [3.004(2)-3.051(2) A] into a Se(4) square, and is structurally analogous to the previously reported Ph(4)Te(4)I(4). The reactions of Ph(4)Se(4)Br(4) with a variety of tertiary phosphines have been undertaken, resulting in the formation of compounds of formula R(3)PSe(Ph)Br. X-Ray crystallographic analysis of three of the compounds reveals different structural isomers. Ph(3)PSe(Ph)Br (2) is a charge-transfer (CT) compound [Se-Br 3.0020(8) A], with an essentially linear P-Se-Br bond angle, 172.15(4) degrees and T-shaped geometry at selenium. Me(3)PSe(Ph)Br (5) also contains the selenium atom in a T-shaped geometry, consistent with a CT formulation, although the Se-Br distance of 3.327(3) A is considerably longer than observed for 2. In contrast, Cy(3)PSe(Ph)Br (6) is an ionic phosphonium salt, [Cy(3)PSePh]Br with no short Se-Br interactions. Geometry at selenium is bent, as expected for an ionic compound. These results are discussed with reference to the previously reported iodo-compounds Ph(3)PSe(Ph)I and [(Me(2)N)(3)PSe(Ph)]I.     

A Comparative Study of Two New Structure Types. Synthesis and Structural and Electronic Characterization of K(RE)P(2)Se(6) (RE = Y, La, Ce, Pr, Gd)

Two polytypes of potassium rare-earth-metal hexaselenodiphosphates(IV), K(RE)P(2)Se(6) (RE = Y, La, Ce, Pr, Gd), have been synthesized from the stoichiometric reaction of RE, P, Se, and K(2)Se(4) at 750 degrees C. Both single-crystal and powder X-ray diffraction analyses showed that the structures of these polytypes vary with the size of the rare earth metals. For the smaller rare-earth metals, Y and Gd, K(RE)P(2)Se(6) crystallized in the orthorhombic space group P2(1)2(1)2(1). The yttrium compound was studied by single-crystal X-ray diffraction with the cell parameters a = 6.7366(5) ?, b = 7.4286(6) ?, c = 21.603(2) ?, and Z = 4. This structure type comprises a layered, square network of yttrium atoms that are bound to four distinct [P(2)Se(6)](4)(-) units through selenium bonding. Each [P(2)Se(6)](4)(-) unit possesses a Se atom that is not bound to any Y atom but is pointing out into the interlayer spacing, into an environment of potassium cations. For larger rare-earth metals, La, Ce, and Pr, K(RE)P(2)Se(6) crystallized in a second, monoclinic polytype, the structure of which has been published. Both of these two different polytypes can be related to each other and several other isoelectronic chalcophosphate structures based on a Parthé valence electron concentration analysis. These structures include Ag(4)P(2)S(6), K(2)FeP(2)S(6), and the hexagonal M(II)PS(3) structure types. The magnetic susceptibilities of the title compounds have been studied, and the behavior can been explained based on a simple set of unpaired f-electrons. The diffuse reflectance spectroscopy also showed that these yellow plates are moderately wide band gap ( approximately 2.75 eV) semiconductors.     

LiEuPSe4 and KEuPSe4: novel selenophosphates with the tetrahedral [PSe4]3- building block

LiEuPSe4, the first quaternary lithium-containing selenophosphate, was synthesized as red polyhedra by reacting Eu with a molten mixture of Li2Se/P2Se5/Se at 750 degrees C. Similarly, the reaction of Eu with a molten mixture of K2Se/P2Se5/Se at 495 degrees C produced red polyhedral crystals of KEuPSe4. Both compounds are unstable in moist air. In addition, both compounds were plagued with crystal twinning. Acceptable crystal structure refinements could only be obtained by identifying the type of twinning and taking it into account in the final refinement. LiEuPSe4 crystallizes in the noncentrosymmetric space group Ama2 (no. 40) with a = 10.5592 (9) A, b = 10.415 (1) A, c = 6.4924(7) A, and Z = 4. The structure is three-dimensional and composed of EuSe8 distorted square antiprisms and PSe4 tetrahedral building blocks that create tunnels, running down the a axis, in which the Li ions reside. The Li ions are in a highly distorted tetrahedral coordination. KEuPSe4 crystallizes in the space group P2(1)/m (no. 11) with a = 6.8469(6) A, b = 6.9521(6) A, c = 9.0436(8) A, beta = 107.677(2) degrees, and Z = 2. The structure has two-dimensional character with layers composed of EuSe6 trigonal prisms and PSe4 tetrahedral units. Between the [EuPSe4]nn- layers the K ions reside in a bicapped trigonal prism of Se atoms. The structure of the [EuPSe4]nn- framework is similar to that found in CsPbPSe4. Both compounds are semiconductors with band gaps of 2.00 and 1.88 eV, respectively. Differential thermal analysis and infrared spectroscopic characterization are also reported.     

Conversion of a Re(IV) tetrahedral cluster to a Re(III) octahedral cluster: synthesis of [(CH3)C(NH2)(2)](4)[Re(6)Se(8)(CN)(6)] by a solvothermal route

The compound [(CH(3))C(NH(2))(2)](4)[Re(6)Se(8)(CN)(6)] has been synthesized by the reaction at 200 degrees C for 3 days of Re(4)Te(4)(TeCl(2))(4)Cl(8), KSeCN, and NH(4)Cl in superheated acetonitrile. This compound crystallizes in the space group C2/c of the monoclinic system with four formula units in a cell of dimensions a = 20.3113(14) A, b = 10.1332(7) A, c = 19.9981(14) A, beta = 106.754(1) degrees, V = 3941.3(5) A(3) (T = 153 K). The [Re(6)Se(8)(CN)(6)](4-) anion comprises an Re(6) octahedron face capped by mu(3)-Se atoms, with each Re atom liganded by a CN group. The anions and cations are connected by an extensive network of hydrogen bonds. The conversion of a Re(IV) tetrahedral cluster to a Re(III) octahedral cluster appears to be unprecedented.     

Two-, three-, and four-coordination at gold(I) supported by the bidentate selenium ligand [Ph2P(Se)NP(Se)Ph2](-)

Treatment of the gold(I) halide complexes LAuCl (L = PMe3, PPh3, CNC6H3Me2-2,6) with K[Ph2P(Se)NP(Se)Ph2] provides the gold-selenium coordination compounds [(N(Ph2PSe)2-Se,Se')AuL]. However, on standing for a number of days, the complex [(N(Ph2PSe)2-Se,Se')AuPMe3] gains a phosphine to provide the bis(phosphine) species [(N(Ph2PSe)2-Se,Se')Au(PMe3)2]. Treatment of the K[Ph2P(Se)NP(Se)Ph2] ligand with [(Ph3PAu)3O]BF4 allows the isolation of [(N(Ph2PSe)2-Se,Se')(AuPPh3)2]BF4. Reaction of the complex [(dppm)(AuCl)2] with AgSO3CF3 followed by addition of the ligand K[Ph2P(Se)NP(Se)Ph2] results in the formation of [(N(Ph2PSe)2-Se,Se')Au2(dppm)]OSO2CF3 and treatment of [(tht)AuCl] (tht = tetrahydrothiophene) with an equimolar quantity of K[Ph2P(Se)NP(Se)Ph2] affords the complex [(N(Ph2PSe)2-Se,Se')2Au2]. The compounds [(N(Ph2PSe)2-Se,Se')Au2(dppm)]OSO2CF3, [(N(Ph2PSe)2-Se,Se')AuPPh3] and [(N(Ph2PSe)2-Se,Se')Au(PMe3)2] have been investigated crystallographically. The results reveal that the metal centers are two-, three-, and four-coordinate, respectively. The cationic, eight-membered ring complex bearing the dppm ligand displays transannular aurophilic bonding and is further associated into dimers via intermolecular gold-selenium contacts. The six-membered rings in the other two structures have C2-symmetrical twist conformations, however, the Au(I) coordination sphere in [N(PPh2Se)2]AuPPh3 is not fully symmetrical. The Au-Se bond lengths increase dramatically as the coordination number of the metal atom becomes larger.     

Selenophosphate phase diagrams developed in conjunction with the synthesis of the new compounds K(2)La(P(2)Se(6))(1/2)(PSe(4)), K(3)La(PSe(4))(2), K(4)La(0.67)(PSe(4))(2), K(9-x)La(1+x/3)(PSe(4))(4) (x = 0.5), and KEuPSe(4)

Five new rare-earth metal polyselenophosphates have been synthesized by the reactive flux method and characterized by single-crystal X-ray diffraction: K(2)La(P(2)Se(6))(1/2)(PSe(4)) (I), K(3)La(PSe(4))(2) (II), K(4)La(0.67)(PSe(4))(2) (III), K(9-x)()La(1+)(x/3)(PSe(4))(4) (x = 0.5) (IV), and KEuPSe(4) (V). Compound I crystallizes in the monoclinic space group P2(1)/n with a = 9.4269(1) A, b = 7.2054(1) A, c = 21.0276(5) A, beta = 97.484(1) degrees, and Z = 4. Compound II crystallizes in the monoclinic space group P2(1)/c with a = 9.5782(2) A, b = 17.6623(4) A, c = 9.9869(3) A, beta = 90.120(1) degrees, and Z = 4. Compound III crystallizes in the orthorhombic space group Ibam with a = 19.0962(2) A, b = 9.1408(1) A, c = 10.2588(2) A, and Z = 4. Compound IV crystallizes in the orthorhombic space group Ccca with a = 18.2133(1) A, b = 38.0914(4) A, c = 10.2665(1) A, and Z = 8. Compound V crystallizes in the orthorhombic space group Pnma with a = 17.5156(11) A, b = 7.0126(5) A, c = 6.9015(4) A, and Z = 4. Optical band gap measurements show that compound V has an optical band gap of 1.88 eV. Solid-state Raman spectroscopy of compounds II-V shows the four normal vibrations expected for the (PSe(4))(3-) unit. The observation of compounds I-V in several reactions has allowed the creation of a quasi-quaternary phase diagram for potassium rare-earth-metal polyselenophosphates. This phase diagram can qualitatively be separated into three regions on the basis of the oxidation state of phosphorus in the crystalline products observed and takes the next step in designing solid-state compounds.     

Synthesis and Re—refinement of Cu3PSe4

1 INTRODUCTION The chemistry of mixed 15/16 main group compounds has attracted great attentions over the last years[1]. The metal chalcogenophosphides synthesized by solid state reactions[2] are the potential candidates for a wide range of applications such as semiconducting properties, two-dimensional magnetic behavior, anisotropy of conductivity and charge density waves. Some of these compounds are of lamellar structure, which are good materials for the investigation of intercalatio…     

The related compounds MThTe3 (M = Mn, Mg) and ACuThSe3 (A = K, Cs): syntheses and characterization

Single crystals of MnThTe3 (1) and MgThTe3 (2) grow as small black plates from the stoichiometric reaction of the elements, the former at 1,000 degrees C and the latter at 900 degrees C with the aid of a Sn flux. Both compounds crystallize in the space group Cmcm of the orthorhombic system with four formula units in cells of dimensions a = 4.2783(6) A, b = 13.8618(11) A, and c = 9.9568(15) A for 1 and a = 4.2854(6) A, b = 14.042(2) A, and c = 9.9450(14) A for 2 at T = 153(2) K. KCuThSe3 (3) forms as red blocks from a stoichiometric mixture of K2Se, Cu, Th, and Se at 800 degrees C, and CsCuThSe3 (4) forms as yellow blocks from a stoichiometric mixture of Cs2Se3, Cu, Th, and Se at 850 degrees C. Compounds 3 and 4 also crystallize in the space group Cmcm of the orthorhombic system with four formula units in cells of dimensions a = 4.1832(8) A, b = 14.335(3) A, and c = 10.859(2) A for 3 and a = 4.2105(7) A, b = 15.715(3) A, and c = 10.897(2) A for 4 at 153(2) K. Compounds 1 and 2 are isostructural with each other as well as with several uranium analogues and comprise pseudolayered structures with slabs of corner-shared MTe6 octahedra alternating with slabs of cap- and edge-shared ThTe8 bicapped trigonal prisms. The slabs are bonded together through the sharing of edges and vertices of the various polyhedra to form three-dimensional structures. Compounds 3 and 4 are two-dimensional layered structures that are closely related to 1 and 2. In 3 and 4, ThSe6 octahedra form the same slabs as MTe6 in 1 and 2 and Cu atoms occupy the tetrahedral holes in the layers. Alkali metal cations occupy bicapped trigonal prismatic sites between the layers. Neither structure type has short Q-Q interactions, and therefore the oxidation states of all atoms are straightforwardly assigned on the assumption of Th4+. Magnetic susceptibility measurements on compound 1 show a ferromagnetic transition at 70 K and a magnetic moment of 5.9(2) muB per Mn ion, indicating low-spin Mn2+.     

Synthesis and characterization of two quaternary thorium chalcophosphates: Cs4Th2P6S18 and Rb7Th2P6Se21

Two new thorium chalcophosphates have been synthesized by the reactive flux method and characterized by single-crystal X-ray diffraction, diffuse reflectance, and Raman spectroscopy: Cs4Th2P6S18 (I); Rb7Th2P6Se21 (II). Compound I crystallizes as colorless blocks in the triclinic space group P1 (No. 2) with a = 12.303(4) A, b = 12.471(4) A, c = 12.541(4) A, alpha = 114.607(8) degrees, beta = 102.547(6) degrees, gamma = 99.889(7) degrees, and Z = 2. The structure consists of (Th2P6S18)(4-) layers separated by layers of cesium cations and only contains the (P2S6)(4-) building block. Compound II crystallizes as red blocks in the triclinic space group P1 (No. 2) with a = 11.531(3) A, b = 12.359(4) A, c = 16.161(5) A, alpha = 87.289(6) degrees, beta = 75.903(6) degrees, gamma = 88.041(6) degrees, and Z = 2. The structure consists of linear chains of (Th2P6Se21)(7-) separated by rubidium cations. Compound II contains both the (PSe4)(3-) and (P2Se6)(4-) building blocks. Both structures may be derived from two known rare earth structures where a rare earth site is replaced by an alkali or actinide metal to form these novel structures. Optical band gap measurements show that compound I has a band gap of 2.8 eV and compound II has a band gap of 2.0 eV. Solid-state Raman spectroscopy of compound I shows the vibrations expected for the (P2S6)(4-) unit. Raman spectroscopy of compound II shows the vibrations expected for both (PSe4)(3-) and (P2Se6)(4-) units. Our work shows the remarkable diversity of the actinide chalcophosphate system and demonstrates the phase space is still ripe to discover new structures.     

The coordination chemistry of selenophosphite ligands. Synthesis and characterization of heterometallic tetranuclear clusters [M{CpFe(CO)(2)P(Se)(OR)(2)}(3)](PF(6)) (M = Cu, Ag; R = (n)Pr, (i)Pr) and [Cu(mu-X) {CpFe(CO)(2)P(Se)(O(i)Pr)(2)}](2) (X = Cl, Br)

A neutral selenium donor ligand, [CpFe(CO)(2)P(Se)(OR)(2)] is used for the construction of Cu(I) and Ag(I) complexes with a well-defined coordination environment. Four clusters [M{CpFe(CO)(2)P(Se)(OR)(2)}(3)](PF(6)), (where M = Cu, R = (n)Pr, ; R = (i)Pr, and M = Ag, R = (n)Pr, ; R = (i)Pr, ) are isolated from the reaction of [M(CH(3)CN)(4)(PF(6))] (where M = Cu or Ag) and [CpFe(CO)(2)P(Se)(OR)(2)] in a molar ratio of 1 : 3 in acetonitrile at 0 degrees C. The reaction of [CpFe(CO)(2)P(Se)(O(i)Pr)(2)] with cuprous halides in acetone produce two mixed-metal, Cu(I)(2)Fe(II)(2) clusters, [Cu(mu-X) {CpFe(CO)(2)P(Se)(O(i)Pr)(2)}](2) (X = Cl, ; Br, ). All six clusters have been fully characterized spectroscopically ((1)H, (13)C, (31)P, and (77)Se NMR, IR), and by elemental analyses. X-Ray crystal structures of and consist of discrete cationic clusters in which three iron-selenophosphito fragments are linked to the central copper or silver atom via selenium atoms. Both clusters and crystallize in the noncentrosymmetric, hexagonal space group P6[combining macron]2c. The coordination geometry around the copper or silver atom is perfect trigonal-planar with Cu-Se and Ag-Se distances, 2.3505(7) and 2.5581(7) A, respectively. X-Ray crystallography also reveals that each copper center in neutral heterometallic clusters and is trigonally coordinated to two halide ions and a selenium atom from the selenophosphito-iron moiety. The structures can also be delineated as a dimeric unit which is generated by an inversion center and has a Cu(2)X(2) parallelogram core. The dihedral angle between the Cu(2)X(2) plane and the plane composed of Cp ring is found to be 24.62 and 84.58 degrees for compound and , respectively. Hence the faces of two opposite Cp rings are oriented almost perpendicular to the Cu(2)X(2) plane in , but are close to be parallel in . This is the first report of the coordination chemistry of the anionic selenophosphito moiety [(RO)(2)PSe](-), the conjugated base of a secondary phosphine selenide, which acts as a bridging ligand with P-coordination on iron and Se-coordination to copper or silver.     

Strontium selenogermanate(III) and barium selenogermanate(II,IV): synthesis, crystal structures, and chemical bonding

The new selenogermanates Sr2Ge2Se5 and Ba2Ge2Se5 were synthesized by heating stoichiometric mixtures of binary selenides and the corresponding elements to 750 degrees C. The crystal structures were determined by single-crystal X-ray methods. Both compounds adopt previously unknown structure types. Sr2Ge2Se5 (P2(1)/n, a = 8.445(2) A, b = 12.302 A, c = 9.179 A, beta = 93.75(3) degrees, Z = 4) contains [Ge4Se10]8- ions with homonuclear Ge-Ge bonds (dGe-Ge = 2.432 A), which may be described as two ethane-like Se3Ge-GeSeSe2/2 fragments sharing two selenium atoms. Ba2Ge2Se5 (Pnma, a = 12.594(3) A, b = 9.174(2) A, c = 9.160(2) A, Z = 4) contains [Ge2Se5]4- anions built up by two edge-sharing GeSe4 tetrahedra, in which one terminal Se atom is replaced by a lone pair from the divalent germanium atom. The alkaline earth cations are arranged between the complex anions, each coordinated by eight or nine selenium atoms. Ba2Ge2Se5 is a mixed-valence compound with GeII and GeIV coexisting within the same anion. Sr2Ge2Se5 contains exclusively GeIII. These compounds possess electronic formulations that correspond to (Sr2+)2(Ge3+)2(Se2-)5 and (Ba2+)2- Ge2+Ge4+(Se2-)5. Calculations of the electron localization function (ELF) reveal clearly both the lone pair on GeII in Ba2Ge2Se5 and the covalent Ge-Ge bond in Sr2Ge2Se5. Analysis of the ELF topologies shows that the GeIII-Se and GeIV-Se covalent bonds are almost identical, whereas the GeII-Se interactions are weaker and more ionic in character.     

Synthesis and characterisation of four- and six-membered P-Se heterocycles

The preparation, spectroscopic characterisation and crystal structures of [FcP(mu-Se)Se]2, [FcP(mu-Se2)Se]2 and [PhP(mu-Se2)Se]2 are reported. Crystallographic data reveal planar four-membered PSePSe and skewed six-membered P2Se4 rings, respectively, in all cases with trans arrangement of organic substituents and exo selenium atoms. Whilst stable at room temperature in solid state, NMR data suggest the six-membered rings of both the ferrocenyl and phenyl compounds decompose in the solution with loss of red selenium, forming PSe2PSe five-membered rings.     

Synthesis, structure, and properties of Cs(4)Th(4)P(4)Se(26): a quaternary thorium selenophosphate containing the (P(2)Se(9))(6-) anion

Orange crystals of Cs(4)Th(4)P(4)Se(26) were grown from the reaction of (232)Th and P in a Cs(2)Se(3)/Se molten salt flux at 750 degrees C. Cs(4)Th(4)P(4)Se(26) crystallizes in the orthorhombic space group Pbca with the unit cell parameters: a = 12.0130(6), b = 14.5747(7), c = 27.134(1) A; Z = 8. The compound exhibits a three-dimensional structure, consisting of dimeric [Th(2)Se(13)] polyhedral units. The two crystallographically independent, nine-coordinate, bicapped trigonal prismatic thorium atoms share a triangular face to form the dimer, and each dimer edge-shares two selenium atoms with two other dimers to form kinked chains along the [010] direction. While this structure shares features of the previously reported Rb(4)U(4)P(4)Se(26), including phosphorus in the 5+ oxidation state, careful inspection of the structure reveals that the selenophosphate anion that knits the structure together in three directions in both compounds is a unique (P(2)Se(9))(6-) anion. The formula may be described best as [Cs(2)Th(2)(P(2)Se(9))(Se(2))(2)](2). The (P(2)Se(9))(6-) anion features a nearly linear Se-Se-Se backbone with an angle of 171 degrees and Se-Se distances that are approximately 0.2-0.3 A longer than the typical single Se-Se bond. Magnetic studies confirm that this phase contains Th(IV). Raman data for this compound is reported, and structural comparisons will be drawn to its uranium analogue, Rb(4)U(4)P(4)Se(26).     

APSe6 (A = K, Rb, and Cs): Polymeric selenophosphates with reversible phase-change properties

The ternary alkali selenophosphates KPSe6 and RbPSe6 crystallize in the polar orthorhombic space group Pca2(1) with a = 11.7764(17) A, b = 6.8580(10) A, c = 11.4596(16) A, and Z = 4 for RbPSe6. CsPSe6 crystallizes in the monoclinic space group P2/n with a = 6.877(3) A, b = 12.713(4) A, c = 11.242(4) A, beta = 92.735(7) degrees, and Z = 4. All compounds feature the one-dimensional infinite chain of [PSe2(Se)4-], where each P atom is connected with Se4(2-) bridge. These compounds show reversible glass-crystal transition, and 31P NMR data suggest that crystallization and infinite [PSe(6-)] chain formation are coupled processes.     

Synthesis, structure, and thermal properties of soluble hydrazinium germanium(IV) and tin(IV) selenide salts

The crystal structures of two hydrazinium-based germanium(IV) and tin(IV) selenide salts are determined. (N(2)H(5))(4)Ge(2)Se(6) (1) [I4(1)cd, a = 12.708(1) Angstroms, c = 21.955(2) Angstroms, Z = 8] and (N(2)H(4))(3)(N(2)H(5))(4)Sn(2)Se(6) (2) [P, a = 6.6475(6) Angstroms, b = 9.5474(9) Angstroms, c = 9.8830(10) Angstroms, alpha = 94.110(2) degrees, beta = 99.429(2) degrees, gamma = 104.141(2) degrees, Z = 1] each consist of anionic dimers of edge-sharing metal selenide tetrahedra, M(2)Se(6)(4-) (M = Ge or Sn), separated by hydrazinium cations and, for 2, additional neutral hydrazine molecules. Substantial hydrogen bonding exists among the hydrazine/hydrazinium molecules as well as between the hydrazinium cations and the selenide anions. Whereas the previously reported tin(IV) sulfide system, (N(2)H(5))(4)Sn(2)S(6), decomposes cleanly to microcrystalline SnS(2) when heated to 200 degrees C in an inert atmosphere, higher temperatures (>300 degrees C) are required to dissociate selenium from 1 and 2 for the analogous preparations of single-phase metal selenides. The metal chalcogenide salts are highly soluble in hydrazine, as well as in a variety of amines and DMSO, highlighting the potential usefulness of these compounds as precursors for the solution deposition of the corresponding metal chalcogenide films.     

Synthesis and Structure of Ag_3PSe_4

The title compound Ag3PSe4 was synthesized by the reaction of Ag powder,P2Se5 and Se in a molar ratio of 1:1:1 at 500℃ and structurally characterized by X-ray crystallography.The crystal belongs to orthorhombic,space group Pmn21 with cell parameters:a=7.689(4),b=6.660(3),c=6.379(4)A,V=326.7(3)A^3,Z=2,Dc=6.816g/cm^3,Mr=670.42,F(000)=584,μ=31.302mm^-1,R=0.0606,wR=0.1289 and S=1.012,The 3-D structure can be regarded as constructed from the stacking of puckered Ag-P-Se honeycomb-like sheets along the c direction,in which the Ag,P and Se atoms are bonded to each other to form a chair-like six-membered ring,and the rings then build the sheets by sharing edges.     

Syntheses and structures of the infinite chain compounds Cs(4)Ti(3)Se(13), Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14)

The alkali metal/group 4 metal/polychalcogenides Cs(4)Ti(3)Se(13), Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14) have been synthesized by means of the reactive flux method at 823 or 873 K. Cs(4)Ti(3)Se(13) crystallizes in a new structure type in space group C(2)(2)-P2(1) with eight formula units in a monoclinic cell at T = 153 K of dimensions a = 10.2524(6) A, b = 32.468(2) A, c = 14.6747(8) A, beta = 100.008(1) degrees. Cs(4)Ti(3)Se(13) is composed of four independent one-dimensional [Ti(3)Se(13)(4-)] chains separated by Cs(+) cations. These chains adopt hexagonal closest packing along the [100] direction. The [Ti(3)Se(13)(4-)] chains are built from the face- and edge-sharing of pentagonal pyramids and pentagonal bipyramids. Formal oxidation states cannot be assigned in Cs(4)Ti(3)Se(13). The compounds Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14) crystallize in the K(4)Ti(3)S(14) structure type with four formula units in space group C(2)(h)()(6)-C2/c of the monoclinic system at T = 153 K in cells of dimensions a = 21.085(1) A, b = 8.1169(5) A, c = 13.1992(8) A, beta = 112.835(1) degrees for Rb(4)Ti(3)S(14);a = 21.329(3) A, b = 8.415(1) A, c = 13.678(2) A, beta = 113.801(2) degrees for Cs(4)Ti(3)S(14); a = 21.643(2) A, b = 8.1848(8) A, c = 13.331(1) A, beta = 111.762(2) degrees for Rb(4)Hf(3)S(14); a = 22.605(7) A, b = 8.552(3) A, c = 13.880(4) A, beta = 110.919(9) degrees for Rb(4)Zr(3)Se(14); a = 22.826(5) A, b = 8.841(2) A, c = 14.278(3) A, beta = 111.456(4) degrees for Cs(4)Zr(3)Se(14); and a = 22.758(5) A, b = 8.844(2) A, c = 14.276(3) A, beta = 111.88(3) degrees for Cs(4)Hf(3)Se(14). These A(4)M(3)Q(14) compounds (A = alkali metal; M = group 4 metal; Q = chalcogen) contain hexagonally closest-packed [M(3)Q(14)(4-)] chains that run in the [101] direction and are separated by A(+) cations. Each [M(3)Q(14)(4-)] chain is built from a [M(3)Q(14)] unit that consists of two MQ(7) pentagonal bipyramids or one distorted MQ(8) bicapped octahedron bonded together by edge- or face-sharing. Each [M(3)Q(14)] unit contains six Q(2)(2-) dimers, with Q-Q distances in the normal single-bond range 2.0616(9)-2.095(2) A for S-S and 2.367(1)-2.391(2) A for Se-Se. The A(4)M(3)Q(14) compounds can be formulated as (A(+))(4)(M(4+))(3)(Q(2)(2-))(6)(Q(2-))(2).     

Selenium oxoanion compounds of palladium(II)

Three new palladium compounds, PdSeO3, PdSe2O5, and Na2Pd(SeO4)2, containing selenium oxoanions of both Se(IV) and Se(VI) have been prepared under mild hydrothermal conditions. PdSe2O5 and Na2Pd(SeO4)2 both possess one-dimensional structures. Within the structure of PdSe2O5, [PdO4] square planar building blocks are joined together through diselenite, Se2O52-, anions, and form a zigzag chain along the c axis. In Na2Pd(SeO4)2, [PdO4] units are connected by two selenate, SeO42-, anions, and extend along the a axis to form a [Pd(SeO4)2]2- chain. Na+ cations reside in the space between the [Pd(SeO4)2]2- chains and act as counter cations. Unlike above two compounds, PdSeO3 exhibits a layered structure. In the structure of PdSeO3, [PdO4] units are connected to each other by corner-sharing and form a zigzag chain along the b axis. The chains are further joined together by tridentate selenite, SeO32-, anions to form layers in the [ab] plane that stack along the c axis. Crystallographic data: (193 K; Mo Kalpha, lambda=0.71073 A): PdSeO3, monoclinic, space group P21/m, a=3.8884(5) A, b=6.4170(8) A, c=6.1051(7) A, beta=96.413(2) degrees, V=151.38(3) A3, Z=2; PdSe2O5, monoclinic, space group C2/c, a=12.198(2) A, b=5.5500(8) A, c=7.200(1) A, beta=107.900(2) degrees , V=463.8(1) A3, Z=4; Na2Pd(SeO4)2, triclinic, space group P, a=4.9349(11) A, b=5.9981(13) A, c=7.1512 (15) A, alpha=73.894(4) degrees, beta=86.124(4) degrees, gamma=70.834(4) degrees, V=192.03(7) A3, Z=1.     

Syntheses and characterization of some mixed Te/Se polychalcogenide anions [Te(m)Se(n)]2-

Several mixed Te/Se polychalcogenide anions [Te(m)Se(n)](2-) were synthesized at 293 K by reactions between Te(n)(2-)and Se(n)(2-) anions in N,N-dimethylformamide (DMF) in the presence of different-size ammonium or phosphonium cations, in some cases in the presence of metal species. The structures of these anions were determined by single-crystal X-ray diffraction methods. The crystal structures of [NEt(4)](2)[Te(3)Se(6)] (1) and [NEt(4)](2)[Te(3)Se(7)] (2) consist, respectively, of one-dimensional infinite 1(infinity)[Te(3)Se(6)(2-)] and 1(infinity)[Te(3)Se(7)(2-)] anionic chains separated by NEt(4)(+) cations. In compound 1, each chain comprises Te(3)Se(5) eight-membered rings bridged by Se atoms. The Te(3)Se(5) ring has an "open book" conformation. The NMR spectrum of a DMF solution of [NEt(4)](2)[Te(3)Se(6)] crystals at 223 K shows (77)Se resonances at delta = 290, 349, and 771 ppm and a single (125)Te resonance at delta = 944.7 ppm. In compound 2, each chain comprises Te(3)Se(6) five- and six-membered rings bridged by Se atoms. The Te(3)Se(6) ring can be regarded as an inorganic analogue of bicyclononane. The anion of [PPh(4)](2)[Te(2)Se(2)] (4) contains a Se-Te-Te-Se chain with the terminal Se atoms trans to one another. The new compounds [PPN](2)[TeSe(10)] (3), [NMe(4)](2)[TeSe(3)].DMF (5), and [NEt(4)](2)[TeSe(3)] (6) contain known anions.