Sulfosalts with alkaline earth metals. Centrosymmetric vs acentric interplay in Ba3Sb4.66S10 and Ba2.62Pb1.38Sb4S10 based on the Ba/Pb/Sb ratio. Phases related to arsenosulfide minerals of the rathite group and the novel polysulfide Sr6Sb6S17

The new compounds, Sr6Sb6S17, Ba2.62Pb1.38Sb4S10, and Ba3Sb4.66S10 were prepared by the molten polychalcogenide salt method. Sr6Sb6S17 crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a = 8.2871(9) A, b = 15.352(2) A, c = 22.873(3) A, and Z = 4. This compound presents a new structure type composed of [Sb3S7]5- units and trisulfide groups, (S3)2-, held together by Sr2+ ions. The [Sb3S7]5- fragment is formed from three corner-sharing SbS3 trigonal pyramids. The trisulfide groups are separated from the [Sb3S7]5- unit and embedded between the Sr2+ ions. Ba3Sb4.66S10 and Ba2.62Pb1.38Sb4S10 are not isostructural but are closely related to the known mineral sulfosalts of the rathite group. Ba3Sb4.67S10 is monoclinic P2(1)/c with a = 8.955(2) A, b = 8.225(2) A, c = 26.756(5) A, beta = 100.29(3) degrees, and Z = 4. Ba2.62Pb1.38Sb4S10 is monoclinic P2(1) with a = 8.8402(2) A, b = 8.2038(2) A, c = 26.7623(6) A, beta = 99.488(1) degrees, and Z = 4. The Sb atoms are stabilized in SbS3 trigonal pyramids that share corners to build ribbonlike slabs, which are stitched by Ba/Pb atoms to form layers perpendicular to the c-axis. These materials are semiconductors and show optical band gaps of 2.10, 2.14, and 1.64 eV for Sr6Sb6S17, Ba3Sb4.66S10, and Ba2.62Pb1.38Sb4S10, respectively. Raman spectroscopic characterization is reported. Sr6Sb6S17, Ba3Sb4.66S10, and Ba2.62Pb1.38Sb4S10 melt congruently at 729, 770, and 749 degrees C, respectively.     

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.     

Structures and physical properties of new semiconducting polyselenides Ba2CudeltaAg4-deltaSe5 with unprecedented linear Se(3)4- units

The title compounds were prepared from the elements in evacuated silica tubes at 650 degrees C, followed by slow cooling. Ba2Ag4Se5 forms a new structure type, space group C2/m, with a=16.189(2) A, b=4.5528(6) A, c=9.2500(1) A, beta=124.572(3) degrees, and V=561.4(1) A3 (Z=2). A maximum of 44% of the Ag atoms may be replaced with Cu atoms without changing the structure type. The crystal structure is composed of Ag4Se(5)4- layers, interconnected via the Ba2+ cations. The Ag atoms show irregular [3+1] coordination by the Se atoms, and the Ba atoms are located in capped square antiprisms formed by Se atoms. Most intriguing is the unprecedented occurrence of linear Se(3)4- units. According to the formulation (Ba2+)2(Ag+)4Se(3)4-(Se2-)2, this selenide is electron-precise with eight positive charges equalizing the eight negative charges. Electronic structure calculations indicated the presence of a band gap, as was experimentally confirmed: the electrical conductivity measurement revealed a gap of 0.6 eV for Ba2CuAg3Se5.     

Ae2Sb2X4F2 (Ae = Sr, Ba): new members of the homologous series Ae2M(1+n)X(3+n)F2 designed from rock salt and fluorite 2D building blocks

We have designed new compounds within the homologous series Ae2F2M(1+n)X(3+n) (Ae = Sr, Ba; M = main group metal; n = integer) built up from the stacking of 2D building blocks of rock salt and fluorite types. By incrementally increasing the size of the rock salt 2D building blocks, we have obtained two new n = 1 members of this homologous series, namely, Sr2F2Sb2Se4 and Ba2F2Sb2Se4. We then succeeded in synthesizing these compounds using a high-temperature ceramic method. The structure refinements from the powder or single-crystal X-ray diffraction data confirmed presence of the expected alternating stacking of fluorite [Ae2F2] (Ae = Sr, Ba) and rock salt [Sb2Se4] 2D building blocks. However the Ba derivative shows a strong distortion of the [Sb2Se4] block and a concomitant change of the Sb atom coordination likely related to the lone-pair activity.     

Sb10Se10]2+, a heteronuclear polycyclic polycation from a room-temperature ionic liquid

Reaction of antimony, selenium, and selenium(IV) chloride in the Lewis acidic ionic liquid [BMIM]Cl/AlCl₃ (BMIM: 1‐n‐butyl‐3‐methylimidazolium) at room temperature yielded air‐sensitive black block‐shaped crystals of [Sb₁₀Se₁₀][AlCl₄]₂. The triclinic unit cell (space group ${P\bar 1}Reaction of antimony, selenium, and selenium(IV) chloride in the Lewis acidic ionic liquid [BMIM]Cl/AlCl(3) (BMIM: 1-n-butyl-3-methylimidazolium) at room temperature yielded air-sensitive black block-shaped crystals of [Sb(10)Se(10)][AlCl(4)](2). The triclinic unit cell (space group P1, a=947.85(2), b=957.79(2), c=1166.31(3)?pm; α=103.622(1), β=110.318(1), γ=99.868(1)°; Z=1) contains the first mixed antimony/selenium polycation, [Sb(10)Se(10)](2+). The centrosymmetric polycyclic cation consists of two realgar-like [Sb(4)Se(4)] cages, which are connected through positively charged, three-bonded selenium atoms with a central [Sb(2)Se(2)] ring. Quantum chemical calculations predict semiconducting behavior of the compound and indicate primarily covalent bonding with varying ionic contribution within the [Sb(10)Se(10)](2+) polycation, while the interactions between the polycation and the [AlCl(4)](-) anions are predominantly ionic. The applicability of the Zintl concept to the chemical bonding in the heteronuclear polycation was evaluated by a thorough quantum chemical analysis.     

Synthesis and Structure of Ba(2)Sn(3)Sb(6), a Zintl Phase Containing Channels and Chains

The new Zintl phase dibarium tritin hexaantimonide, Ba(2)Sn(3)Sb(6) has been synthesized, and its structure has been determined by single-crystal X-ray diffraction methods. It crystallizes in the orthorhombic space group -Pnma with a = 13.351(1) ?, b = 4.4100(5) ?, c = 24.449(3) ?, and Z = 4 (T = -50 degrees C). The structure of Ba(2)Sn(3)Sb(6) comprises large channels [010] defined by 30-membered rings constructed from an anionic framework. This framework is built up from Sn-centered trigonal pyramids and tetrahedra, as well as zigzag chains of Sb atoms. Within the channels reside the Ba(2+) cations and additional isolated zigzag Sb-Sb chains. The simultaneous presence of Sn trigonal pyramids and tetrahedra implies that Ba(2)Sn(3)Sb(6) is a mixed-valence compound whose oxidation state notation can be best represented as (Ba(2+))(2)[(Sn(II))(2)(Sn(IV))(Sb(-)(III))(3)(Sb(-)(I))](2)(-)[(Sb(-)(I))(2)](2)(-).     

Mixed-valent selenidoantimonates(III,V) with transition-metal complexes as counterions: solvothermal syntheses and characterization of [M(dien)2]2Sb4Se9 (M = Mn, Fe), [Co(dien)2]2Sb2Se6, and [Ni(dien)2]2Sb2Se5

Novel selenidoantimonate compounds [M(dien)2]2Sb4Se9 [M = Mn (1), Fe (2)], [Co(dien)2]2Sb2Se6 (3), and [Ni(dien)2]2Sb2Se5 (4) (dien = diethylenetriamine) were solvothermally synthesized and characterized. The unique features of compounds 1-3 are the mixed-valent anionic structures constructed by the Sb(III)Se3 trigonal pyramid and Sb(V)Se4 tetrahedron. Three Sb(III)Se3 pyramids share common corners, forming a heterocyclic Sb3Se6 moiety, and the Sb3Se6 moieties are further connected with Sb(V)Se4 tetrahedra to form the novel one-dimensional [Sb4Se9(4-)]n anionic chain in 1 and 2. The discrete [Sb2Se6]4- anion in 3 is formed by an Sb(III)Se3 trigonal pyramid and an Sb(V)Se4 tetrahedron sharing a common corner. The [Sb2Se5]4- anion in 4 is composed of two Sb(III)Se3 trigonal pyramids connected in the same manner as the [Sb2Se6]4- anion. The mixed-valent [Sb4Se9(4-)]n and [Sb2Se6]4- anions were not observed before. The synthesis and solid-state structural studies of the title compounds show that the transition-metal complexes exhibit different structure-directing effects on the formation of selenidoantimonates in dien. Extensive N-H...Se hydrogen bonds are observed between cations and anions in compounds 1-4, resulting in three-dimensional network structures. Optical and thermal properties of the compounds are reported.     

Ba2AgInS4 and Ba4MGa5Se12 (M = Ag, Li): syntheses, structures, and optical properties

The first two members in alkaline-earth/group XI/group XIII/chalcogen system, namely Ba(2)AgInS(4) and Ba(4)AgGa(5)Se(12), were synthesized along with a Li analogue Ba(4)LiGa(5)Se(12). Ba(2)AgInS(4) crystallizes in space group P2(1)/c. It contains [AgInS(4)](4-) layers built from AgS(3) triangles and InS(4) tetrahedra with Ba(2+) cations inserted between the layers. Ba(4)AgGa(5)Se(12) and Ba(4)LiGa(5)Se(12) adopt two closely-related structure types in space group P4[combining macron]2(1)c with structural difference originating from the different positions of Ag and Li in them. The three-dimensional framework in Ba(4)AgGa(5)Se(12) is composed of GaSe(4) tetrahedra with the Ba and Ag atoms occupying the large and small channels respectively, whereas that in Ba(4)LiGa(5)Se(12) is built from LiSe(4) and GaSe(4) tetrahedra with channels to accommodate the Ba atoms. As deduced from the diffuse reflectance spectra measurement, the optical band gaps were 2.32 (2) eV, 2.52 (2) eV, and 2.65 (2) eV for Ba(2)AgInS(4), Ba(4)AgGa(5)Se(12), and Ba(4)LiGa(5)Se(12), respectively.     

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).     

Synthesis and Characterization of a New Quaternary Selenide Ba_4Sn_3GeSe_9 Containing [SnGeSe_5]~(4-) and [Sn_2Se_4]~(4-) Units

A new quaternary selenide Ba|_4Sn_3GeSe_9 was synthesized by high temperature solid state reaction method and fully characterized by elemental analysis, UV-vis spectrum, and single-crystal X-ray diffraction. The title compound crystallizes in the orthorhombic space group Pnma with a = 12.463(3), b = 9.308(2) and c = 17.892(5) ?. Ba|_4Sn_3GeSe_9 can be characterized by a zero-dimensional compound composed by special [GeSnSe_5]~(4-) units, [Sn_2Se_4]~(4-) units and the adjacent cations Ba~(2+) ions. The [GeSn Se5]4-unit is composed of a SnSe_3 trigonal pyramid formed by divalent Sn~(2+) and edge-sharing with a GeSe_4 tetrahedron, and the [Sn_2Se_4]-unit is composed of two Sn Se_3 trigonal pyramids. Ba|_4Sn_3GeSe_9 is an indirect semiconductor with a band gap of 1.21 eV.     

CRYSTAL STRUCTURE OF HETEROPOLY TUNGSTOANTIMONATE (NH4)_12[Cu3(H_2O)_3Sb_2W_18O_56]·9H_2O

<正> (NH4)12[Cu3(H2O)3Sb2W18O66].9H2O,Mr = 5232.06, orthorhombic, space group Pmcn, a=15.423(4), b = 19.307(6), c = 30.275(6) A,V= 9015.0 A3, Z=4,Dc=3.866 g/cm3,u= 247.569 cm-1,R = 0.064 for 2652 observed reflections [I> 3σ(I)]. X-ray analysis shows that the heteropoly anion of the title compound consists of two α-β-SbW9O33 subunits, which are derived from the a-Keggin structure by loss of one W3O13 group constituted by three edge-sharing WO6 octahedra, merged together through the connection with three CuO4(H2O) units with the O atoms shared with the W atoms.     

THE CRYSTAL STRUCTURE OF TR1S (μ-SULFJDO)-(U3-SULFJDO)-TETRAKTS (O,O-DIETHYLPHOSPHORODITHIOATO-S,S)-OXAZOLE-TRI-MOLYBDENUM-ANTIMONOUSCHLORID {Mo_3(U3-S)[u-S)_3·SbCl_3][S_2P(OEt)_2]_4·(C_3H_3ON)}

<正> Mr = 1445.67, triclinic. The space group is P1 with the unit cell parameters: a = 10.342(3), b = 11.994(3), c = 21.352(4) A; (?)= 76.27(2), β - 88.55(2)°, r = 73.26(2)°; V = 246lA3, Z = 2, DC = 1.959 g.cm-3. The final R factor is 0.068 based on 4053 reflectioons with I≥3(?)(Ⅰ). The title compound may be regarded as the result of that a molecule of trinuclear Mo cluster {Mo3S4[S2P(OEt)2]4·(C3H3ON)}[1] connects with a molecule of SbCl3 by three bridging S atoms. The skeleton {Mo3SbS4} is a distorted cube. The distances of Mo-Mo bonds are 2.728(2), 2,743(2) and 2.751(2) A, respectively, and the distances between Sb and Mo atoms are 3.814(2), 3.815(2) and 3.847(2) A, respectively.     

Ba5Ga4Se10: a new selenidogallate containing the novel [Ga4Se10](10-) anionic cluster with Ga in a mixed-valence state

The new compound Ba(5)Ga(4)Se(10) has been synthesized for the first time. It crystallizes in the tetragonal space group I4/mcm with a = 8.752(2) ?, c = 13.971(9) ?, and Z = 2. The structure contains discrete [Ga(4)Se(10)](10-) anions and charge-compensating Ba(2+) cations. The novel highly anionic [Ga(4)Se(10)](10-) cluster is composed of two Ga(Se)(4) tetrahedra and two Ga(Ga)(Se)(3) tetrahedra with Ga in the 2+/3+ valence states. It also exhibits an unusually long Ga-Se distance of 2.705(2) ?, which has only been observed under high pressure conditions before. A band gap of 2.20(2) eV was deduced from the UV/vis diffuse reflectance spectrum.     

Solvothermal syntheses, crystal structures, and thermal properties of new manganese thioantimonates(III): The first example of the thermal transformation of an amine-rich thioantimonate into an amine-poorer thioantimonate

Two new neutral thioantimonates(III) were first prepared by the reaction of elemental manganese, antimony, and sulfur in tren (tren = tris(2-aminoethyl)amine, C6H18N4) at 140 degrees C. In the amine-rich compound [Mn(tren)]2Sb2S5 (1) the trigonal SbS3 pyramids are connected via common corners (S(3)) into the tetradentate [Sb2S4]4- anion. Four S atoms have bonds to the manganese atoms of the [Mn(tren)2+] cations. A special structural feature is the large Sb-S(3)-Sb(a) angle of 134 degrees. Density functional calculations clearly demonstrate that this large angle results from the steric interactions between the two Mn(tren) subunits. In the crystal structure of the amine-poorer compound [Mn(tren)]2Mn2Sb4S10 (2), MnS4 tetrahedra and SbS3 pyramids are linked via common corners and edges to form a new heterometallic [Mn2Sb4S10] core. The [Mn(C6H18N4)2+] cations are located at the periphery of the core and are bound to the [Mn2Sb4S10] unit via two S atoms. The thermal behavior of both compounds was investigated using simultaneous thermogravimetry (TG), differential thermoanalysis, and mass spectroscopy. The amine-richer compound 1 decomposes in three steps upon heating. After the first TG step an intermediate phase is formed, which was identified as the amine-poorer compound 2 by X-ray diffraction. Reaction of compound 2 at 140 degrees C with an excess of tren forms the amine-rich compound 1.     

Preparation and Structures of the 2.2.2-Cryptand(1+) Salts of the [Sb(2)Se(4)](2)(-), [As(2)S(4)](2)(-), [As(10)S(3)](2)(-), and [As(4)Se(6)](2)(-) Anions

2.2.2-Cryptand(1+) salts of the [Sb(2)Se(4)](2)(-), [As(2)S(4)](2)(-), [As(10)S(3)](2)(-), and [As(4)Se(6)](2)(-) anions have been synthesized from the reduction of binary chalcogenide compounds by K in NH(3)(l) in the presence of the alkali-metal-encapsulating ligand 2.2.2-cryptand (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane), followed by recrystallization from CH(3)CN. The [Sb(2)Se(4)](2)(-) anion, which has crystallographically imposed symmetry 2, consists of two discrete edge-sharing SbSe(3) pyramids with terminal Se atoms cis to each other. The Sb-Se(t) bond distance is 2.443(1) ?, whereas the Sb-Se(b) distance is 2.615(1) ? (t = terminal; b = bridge). The Se(b)-Sb-Se(t) angles range from 104.78(4) to 105.18(5) degrees, whereas the Se(b)-Sb-Se(b) angles are 88.09(4) and 88.99(4) degrees. The (77)Se NMR data for this anion in solution are consistent with its X-ray structure (delta 337 and 124 ppm, 1:1 intensity, -30 degrees C, CH(3)CN/CD(3)CN). Similar to this [Sb(2)Se(4)](2)(-) anion, the [As(2)S(4)](2)(-) anion consists of two discrete edge-sharing AsS(3) pyramidal units. The As-S(t) bond distances are 2.136(7) and 2.120(7) ?, whereas the As-S(b) distances range from 2.306(7) to 2.325(7) ?. The S(b)-As-S(t) angles range from 106.2(3) to 108.2(3) degrees, and the S(b)-As-S(b) angles are 88.3(2) and 88.9(2) degrees. The [As(10)S(3)](2)(-) anion has an 11-atom As(10)S center composed of six five-membered edge-sharing rings. One of the three waist positions is occupied by a S atom, and the other two waist positions feature As atoms with exocyclic S atoms attached, making each As atom in the structure three-coordinate. The As-As bond distances range from 2.388(3) to 2.474(3) ?. The As-S(t) bond distances are 2.181(5) and 2.175(4) ?, and the As-S(b) bond distance is 2.284(6) ?. The [As(4)Se(6)](2)(-) anion features two AsSe(3) units joined by Se-Se bonds with the two exocyclic Se atoms trans to each other. The average As-Se(t) bond distance is 2.273(2) ?, whereas the As-Se(b) bond distances range from 2.357(3) to 2.462(2) ?. The Se(b)-As-Se(t) angles range from 101.52(8) to 105.95(9) degrees, and the Se(b)-As-Se(b) angles range from 91.82(7) to 102.97(9) degrees. The (77)Se NMR data for this anion in solution are consistent with its X-ray structure (delta 564 and 317 ppm, 3:1 intensity, 25 degrees C, DMF/CD(3)CN).     

Cs3AgAs4Se8 and CsAgAs2Se4: selenoarsenates with infinite 1 infinity[AsSe2]- chains in different Ag+ coordination environments

Two quaternary silver selenoarsenates Cs3AgAs4Se8 (I) and CsAgAs2Se4 (II) have been discovered by methanothermal reaction of Li3AsSe3 with AgBF4 in the presence of the respective alkali metal sources Cs2CO3 and CsCl. Orange crystals of Cs3AgAs4Se8 (I) were formed after reaction at 120 degrees C for 72 h, whereas red CsAgAs2Se4 (II) was obtained under slightly different conditions at 140 degrees C for 70 h. Both compounds possess novel two-dimensional (2D) polyanions consisting of infinite 1 infinity[AsSe2]- chains that are interconnected by Ag+ ions in different coordination patterns. In I, a double layer of 1 infinity[AsSe2]- chains is bridged by distorted trigonal planar coordinated Ag+ atoms to form a 2 infinity[AgAs4Se8]3- layer with a thickness of about 11.3 A. The nonbonding Ag...Ag distances are about 4.220 A, and large cavities within the layers accommodate for three of the four crystallographic Cs+ cations. The double amount of Ag+ atoms per AsSe2 chain unit in II leads to simple layers 2 infinity[AgAs2Se4]- [=[Ag2As4Se8]2-] in which the Ag+ atoms are arranged in rows between the 1 infinity[AsSe2]- chains, with alternating Ag...Ag distances of 3.053(3) and 3.488(3) A. Hereby the 1 infinity[AsSe2]- polyanions show a disorder within the central (-As-Seb)- chain (b = bridging), while the positions of the terminal Se atoms (Set) remain unaffected. The thermal, optical, and spectroscopic properties of the compounds are reported. Both I and II melt with decomposition and are wide band gap semiconductors with values of 2.07 and 1.79 eV, respectively. Raman spectroscopic data show typical band patterns expected for infinite [AsSe2]- chains. Crystal Data: Cs3AgAs4Se8 (I), monoclinic, C2/c, a = 25.212(2) A, b = 8.0748(7) A, c = 22.803(2) A, beta = 116.272(2) degrees, Z = 8; CsAgAs2Se4 (II), monoclinic, P2(1)/n, a = 10.9211(1) A, b = 6.5188(2) A, c = 13.7553(3) A, beta = 108.956(1) degrees, Z = 4.     

Crystal structure and physical properties of the new chalcogenides Ba3Cu(17-x)(S,Te)11 and Ba3Cu(17-x)(S,Te)11.5 with two different Cu clusters

The sulfide-tellurides Ba(3)Cu(17-x)(S,Te)(11) and Ba(3)Cu(17-x)(S,Te)(11.5) were synthesized from the elements in stoichiometric ratios heated to 1073 K, followed by slow cooling to 873 K over 100 h. Ba(3)Cu(17-x)(S,Te)(11) is isostructural to Ba(3)Cu(17-x)(Se,Te)(11) when [S] > [Te], space group R ?3m, with lattice dimensions of a = 12.009(1) ?, c = 27.764(2) ?, V = 3467.6(5) ?(3), for Ba(3)Cu(15.7(4))S(7.051(5))Te(3.949) (Z = 6). The structure is composed of Cu atoms forming paired hexagonal antiprisms, capped on the two outer hexagonal faces, where each Cu atom is tetrahedrally coordinated by four Q (= S, Te) atoms. The new variant is formed when [Te] > [S]; then Ba(3)Cu(17-x)(S,Te)(11.5) adopts space group Fm3?m with a = 17.2095(8) ?, V = 5096.9(4) ?(3), for Ba(3)Cu(15.6(2))S(5.33(4))Te(6.17) (Z = 8). This structure consists of eight Te-centered Cu(16) icosioctahedra per cell interconnected by cubic Cu(8) units centered by Q atoms. Electronic structure calculations and property measurements illustrate that these compounds behave as extrinsic p-type semiconductors-toward metallic behavior for the latter compound. With standard oxidation states Ba(2+), Cu(+), and Q(2-), the electron precise formulas are Ba(3)Cu(16)Q(11) and Ba(3)Cu(17)Q(11.5).     

Heterometallic cuboidal clusters M(3)M'Q(4) (M = Mo, W; M'= Sn, Pb, As, Sb; Q = S, Se): from coordination compounds to supramolecular adducts

Reactions of the incomplete cuboidal clusters [M3Q4(acac)3(py)3]+ (M = Mo, W; Q = S, Se) with group 14 and 15 metal complexes with the s2p0 electronic configuration (AsPh3, SbPh3, SbCl3, SbI3, PbI3-, SnCl3-) led to heterometal incorporation with the formation of cuboidal clusters of the type [M3(EX3)Q4(acac)3(py)3]n+ (n = 0 for Sn, Pb; n = 1 for As, Sb), whose structures were determined by X-ray diffraction. The cuboidal clusters can be described as complexes of the cluster tridentate ligand [M3Q4(acac)3(py)3]+ (mu2-chalcogen atoms as donors) with the EX3, where the E atom attains a distorted octahedral coordination. Analysis based on the bond distances E-Q gives the following sequence of affinity: As < Sb; Pb < Sn approximately Sb; SbPh3 < SbI3 approximately SbCl3; W3S4 < W3Se4. Interaction energies at the gas phase between [W3Q4(acac)3(py)3]+ (Q = S, Se) and SbX3 (X = I, Ph) were computed at the DFT level (BP86/TZP). The magnitude of the interaction depends strongly on the substituents at Sb, and the replacement of iodine by the phenyl group decreases the interaction energy from -9.21 to -2.70 kcal/mol and from -12.73 to -3.85 kcal/mol for the W3SbS4 and W3SbSe4 cores, respectively.     

Metastable Se6 as a ligand for Ag+: from isolated molecular to polymeric 1D and 2D structures

Attempts to prepare the hitherto unknown Se(6)(2+) cation by the reaction of elemental selenium and Ag[A] ([A](-) = [Sb(OTeF(5))(6)](-), [Al(OC(CF(3))(3))(4)](-)) in SO(2) led to the formation of [(OSO)Ag(Se(6))Ag(OSO)][Sb(OTeF(5))(6)](2)1 and [(OSO)(2)Ag(Se(6))Ag(OSO)(2)][Al(OC(CF(3))(3))(4)](2)2a. 1 could only be prepared by using bromine as co-oxidant, however, bulk 2b (2a with loss of SO(2)) was accessible from Ag[Al(OC(CF(3))(3))(4)] and grey Se in SO(2) (chem. analysis). The reactions of Ag[MF(6)] (M = As, Sb) and elemental selenium led to crystals of 1/∞{[Ag(Se(6))](∞)[Ag(2)(SbF(6))(3)](∞)} 3 and {1/∞[Ag(Se(6))Ag](∞)}[AsF(6)](2)4. Pure bulk 4 was best prepared by the reaction of Se(4)[AsF(6)](2), silver metal and elemental selenium. Attempts to prepare bulk 1 and 3 were unsuccessful. 1-4 were characterized by single-crystal X-ray structure determinations, 2b and 4 additionally by chemical analysis and 4 also by X-ray powder diffraction, FT-Raman and FT-IR spectroscopy. Application of the PRESTO III sequence allowed for the first time (109)Ag MAS NMR investigations of 4 as well as AgF, AgF(2), AgMF(6) and {1/∞[Ag(I(2))](∞)}[MF(6)] (M = As, Sb). Compounds 1 and 2a/b, with the very large counter ions, contain isolated [Ag(Se(6))Ag](2+) heterocubane units consisting of a Se(6) molecule bicapped by two silver cations (local D(3d) sym). 3 and 4, with the smaller anions, contain close packed stacked arrays of Se(6) rings with Ag(+) residing in octahedral holes. Each Ag(+) ion coordinates to three selenium atoms of each adjacent Se(6) ring. 4 contains [Ag(Se(6))(+)](∞) stacks additionally linked by Ag(2)(+) into a two dimensional network. 3 features a remarkable 3-dimensional [Ag(2)(SbF(6))(3)](-) anion held together by strong Sb-FAg contacts between the component Ag(+) and [SbF(6)](-) ions. The hexagonal channels formed by the [Ag(2)(SbF(6))(3)](-) anions are filled by stacks of [Ag(Se(6))(+)](∞) cations. Overall 1-4 are new members of the rare class of metal complexes of neutral main group elemental clusters, in which the main group element is positively polarized due to coordination to a metal ion. Notably, 1 to 4 include the commonly metastable Se(6) molecule as a ligand. The structure, bonding and thermodynamics of 1 to 4 were investigated with the help of quantum chemical calculations (PBE0/TZVPP and (RI-)MP2/TZVPP, in part including COSMO solvation) and Born-Fajans-Haber-cycle calculations. From an analysis of all the available data it appears that the formation of the usually metastable Se(6) molecule from grey selenium is thermodynamically driven by the coordination to the Ag(+) ions.     

Bonding, structure, and energetics of gaseous E8(2+) and of solid E8(AsF6)2 (E = S, Se)

The attempt to prepare hitherto unknown homopolyatomic cations of sulfur by the reaction of elemental sulfur with blue S8(AsF6)2 in liquid SO2/SO2ClF, led to red (in transmitted light) crystals identified crystallographically as S8(AsF6)2. The X-ray structure of this salt was redetermined with improved resolution and corrected for librational motion: monoclinic, space group P2(1)/c (No. 14), Z = 8, a = 14.986(2) A, b = 13.396(2) A, c = 16.351(2) A, beta = 108.12(1) degrees. The gas phase structures of E8(2+) and neutral E8 (E = S, Se) were examined by ab initio methods (B3PW91, MPW1PW91) leading to delta fH theta[S8(2+), g] = 2151 kJ/mol and delta fH theta[Se8(2+), g] = 2071 kJ/mol. The observed solid state structures of S8(2+) and Se8(2+) with the unusually long transannular bonds of 2.8-2.9 A were reproduced computationally for the first time, and the E8(2+) dications were shown to be unstable toward all stoichiometrically possible dissociation products En+ and/or E4(2+) [n = 2-7, exothermic by 21-207 kJ/mol (E = S), 6-151 kJ/mol (E = Se)]. Lattice potential energies of the hexafluoroarsenate salts of the latter cations were estimated showing that S8(AsF6)2 [Se8(AsF6)2] is lattice stabilized in the solid state relative to the corresponding AsF6- salts of the stoichiometrically possible dissociation products by at least 116 [204] kJ/mol. The fluoride ion affinity of AsF5(g) was calculated to be 430.5 +/- 5.5 kJ/mol [average B3PW91 and MPW1PW91 with the 6-311 + G(3df) basis set]. The experimental and calculated FT-Raman spectra of E8(AsF6)2 are in good agreement and show the presence of a cross ring vibration with an experimental (calculated, scaled) stretching frequency of 282 (292) cm-1 for S8(2+) and 130 (133) cm-1 for Se8(2+). An atoms in molecules analysis (AIM) of E8(2+) (E = S, Se) gave eight bond critical points between ring atoms and a ninth transannular (E3-E7) bond critical point, as well as three ring and one cage critical points. The cage bonding was supported by a natural bond orbital (NBO) analysis which showed, in addition to the E8 sigma-bonded framework, weak pi bonding around the ring as well as numerous other weak interactions, the strongest of which is the weak transannular E3-E7 [2.86 A (S8(2+), 2.91 A (Se8(2+)] bond. The positive charge is delocalized over all atoms, decreasing the Coulombic repulsion between positively charged atoms relative to that in the less stable S8-like exo-exo E8(2+) isomer. The overall geometry was accounted for by the Wade-Mingos rules, further supporting the case for cage bonding. The bonding in Te8(2+) is similar, but with a stronger transannular E3-E7 (E = Te) bonding. The bonding in E8(2+) (E = S, Se, Te) can also be understood in terms of a sigma-bonded E8 framework with additional bonding and charge delocalization occurring by a combination of transannular n pi *-n pi * (n = 3, 4, 5), and np2-->n sigma * bonding. The classically bonded S8(2+) (Se8(2+) dication containing a short transannular S(+)-S+ (Se(+)-Se+) bond of 2.20 (2.57) A is 29 (6) kJ/mol higher in energy than the observed structure in which the positive charge is delocalized over all eight chalcogen atoms.