Synthesis,structure, physical properties,and electronic structure of KGaSe2

The ternary gallium selenide KGaSe₂ has been synthesized by solid-state reactions and good quality crystal has been obtained. KGaSe₂ crystallizes in the monoclinic space group C2/c with cell dimensions of a = 10.878(2) Å, b = 10.872(2) Å, c = 15.380(3) Å, and β = 100.18(3)°. In the structure, adamantane like [Ga₄Se₁₀]⁸⁻ units are connected by common corners forming two-dimensional [GaSe₂]⁻ layers which are separated by K⁺ cations. KGaSe₂ exhibits congruent-melting behavior at around 965 °C. It is transparent in the range of 0.47–20.0 μm and has a band gap of 2.60(2) eV. From a band structure calculation, KGaSe₂ is a direct-gap semiconductor. The band gap is mainly determined by the [GaSe₂]⁻ layer.     

Organic derivatives of tin (II/IV): Investigation of their structure

The structures of tin(II)-oxalate, tin(IV)Na–EDTA and tin(IV)Na₈-inositol hexaphosphate were investigated using XRD analysis. Samples were identified using the Mössbauer study, thermal analysis and FTIR spectrometry. The Mössbauer study determined two different oxidation states of tin atoms, and consequently two different tin surroundings in the end products. The tin oxalate was found to be orthorhombic with space group Pnma, a=9.2066(3) Å, b=9.7590(1) Å, c=13.1848(5) Å, V=1184.62 Å³ and Z=8. SnNa–EDTA was found to be monoclinic with space group P2₁/c₁, a=10.7544(3) Å, b=10.1455(3) Å, c=16.5130(6) Å, β=98.59(2)°, V=1781.50(4) Å³ and Z=4. Sn(C₆H₆Na₈O₂₄P₆) was found to be amorphous.     

One-dimensional coordination polymers generated from an oxadiazole-containing N,N′-bipyridine-type ligand and inorganic salts

Three new one-dimensional coordination polymers have been prepared using Hg(II), Ag(I) and Zn(II) inorganic salts in combination with 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L6). The compounds were characterized by single crystal X-ray diffraction, IR spectroscopy, and elemental analysis. In the solid state, compounds 1 and 3 (1: monoclinic, P2₁/n, a=5.5373(3) Å, b=16.7839(9) Å, c=16.8120(9) Å, β=92.8610(10)°, V=1560.52(15) ų, Z=4; 3: monoclinic, P2₁/n, a=7.2958(4) Å, b=11.7214(6) Å, c=16.3979(9) Å, β=101.1150(10)°, V=1375.99(13) Å³, Z=4) feature novel one-dimensional helical chain motif. Compound 2, however, (2: monoclinic, P2₁/c, a=5.5506(4) Å, b=16.5895(12) Å, c=16.6871(11) Å, β=95.424(2)°, V=1529.70(19) ų, Z=4) exhibits one-dimensional zigzag chain motif, which result from the different conformations adopted by the L6 ligand and also the different metal coordination geometry. The luminescent properties of three new compounds were investigated in the solid state.     

Two coordination polymers of manganese(II) isophthalate and their preparation,structures, and magnetic properties

Two manganese coordination polymers, [Mn₂(ip)₂(dmf)]·dmf (1) and [Mn₄(ip)₄(dmf)₆]·2dmf (2) (ip=isophthalate; dmf=N,N-dimethylformamide), have been synthesized and characterized. X-ray crystal structural data reveal that compound 1 crystallizes in triclinic space group P?1, a=9.716(3) Å, b=12.193(3) Å, c=12.576(3) Å, α=62.19(2)°, β=66.423(17)°, γ=72.72(2)°, Z=2, while compound 2 crystallizes in monoclinic space group Cc, a=19.80(3) Å, b=20.20(2) Å, c=18.01(3) Å, β=108.40(4)°, Z=4. Variable-temperature magnetic susceptibilities of compounds 1 and 2 exhibit overall weak antiferromagnetic coupling between the adjacent Mn(II) ions.     

Metal thiolate compounds: Processable ceramic precursors

Full crystallographic characterization has been obtained for [Hg(SBz)₂]_∞ (9), ClHgSBz · TMEDA (10), [ClHgS-i-Pr]_∞ (11), [ClHg(S-neo-Pent)·0.5Py]_∞ (12), In[S-2,4,6-(i-Pr)₃C₆H₂]₃·2MeCN (13), [In(S-2-MeO,5-Me, C₆H₃)₃]₂ (14) and In(S-o-C₆H₄CH₂N(CH₃)₂)₃ (15). Relevent metal thiolate interactions, terminal and bridging, are highlighted within the realm of thermolytic conversion of these species into binary metal thiolates. Pertinent crystallographic data for these compounds include:9: C2/c,a=22.599(4)Å,b=4.334(1)Å,c=29.596(5)Å,β=106.76(1)°,V=2775.6ų,Z=8,R=3.6%;10: P $\bar 1$ ,a=8.136(2)Å,b=9.958(7)Å,c=11.834(3)Å,α=108.71(2)°,β=92.93(2)°,γ=109.05(2)°,V=845.3ų,Z=2,R=5.0%;11: C2,a=21.430(7)Å,b=4.678(2)Å,c=6.724(2)Å,β=90.43°,V=674.0ų,Z=2,R=3.9%;12: C2,a=16.732(2)Å,b=11.200(1)Å,c=11.929(2)Å,β=104.21(1)°,V=2167.1ų,Z=4,R=3.5%;13: P $\bar 1$ ,a=13.680(8)Å,b=13.815(6)Å,c=15.155(9)Å,α=77.77(4)°,β=72.57(4)°,γ=88.18(4)°,V=2669.1ų,Z=8,R=12.0%;14: C2,a=8.323(2)Å,b=24.970(4)Å,c=12.466(2)Å,β=104.32(2)°,V=2510.1ų,Z=4,R=8.2%;15: P2₁/c,a=17.587(5)Å,b=11.786(2)Å,c=13.865(2)Å,β=101.66(2)°,V=2814.6ų,Z=4,R=3.2%. The molecules-to-materials transition, from a relatively simple divalent system, to the more mechanistically complex trivalent metal system is outlined.     

New gallium pentaphosphates: AGa2P5O16 (A=Rb,Cs)

Gallium pentaphosphates have been synthesized for the first time. These compounds, RbGa₂P₅O₁₆ and CsGa₂P₅O₁₆, are isotypic to the cesium pentaphosphates CsM₂P₅O₁₆ (M=Fe, V). They crystallize in the noncentrosymmetric Pn space group with a=7.4058(3) Å, b=9.2151(2) Å, c=10.0912(11) Å, β=110.768(8)°, V=643.9(1) Å³ (Z=2) and a=7.462(2) Å, b=9.241(3) Å, c=10.103(2) Å, β=110.731(16)°, V=651.5(3) Å³ (Z=2) for the rubidium and cesium compounds, respectively. The single crystal structure determination shows that the 3D [Ga₂P₅O₁₆]_∞ framework is rather rigid and does not vary significantly whatever M=Fe, V, Ga and A=Rb, Cs. The strongly distorted character of the pentaphosphate unit may be at the origin of strains along the P₅O₁₆ group, which explains the difficulty to stabilize pentaphosphates.     

Hydrothermal preparation,structure and characterizations of noncentrosymmetric LiZnO(IO3)

A new lithium zinc iodate, LiZnO(IO₃), has been prepared by hydrothermal reactions at 200 °C. Single-crystal X-ray diffraction experiment revealed that the compound crystallizes in a noncentrosymmetric orthorhombic space group Ama2 with cell parameters: a = 6.3386(6) Å, b = 11.2613(11) Å, c = 4.6840(5) Å, Z = 4. In the structure, the basic building units are the distorted ZnO₆ octahedron, LiO₄ tetrahedron and the IO₃ group. These groups are linked together to form a three-dimensional structure by sharing the oxygen atoms. The DSC measurement demonstrates that the compound is stable up to 490 °C. Powder second-harmonic generation (SHG) test shows that the SHG effect is about 2 × KH₂PO₄.     

Pressure–temperature phase diagram of SeO2. Characterization of new phases

We have investigated SeO₂ at high pressures and high temperatures. Two new phases (β-SeO₂ and γ-SeO₂) and the boundary separating them have been found, following experimental runs performed at pressures up to 15 GPa and temperatures up to 820°C. The two phases crystallize in the orthorhombic system in space group Pmc2₁ (no. 26) with a=5.0722(1) Å, b=4.4704(1) Å, c=7.5309(2) Å, V=170.760(9) Å³ and Z=4 for the β-phase, and with a=5.0710(2) Å, b=4.4832(2) Å, c=14.9672(6) Å, V=340.27(3) Å³ and Z=8 for the γ-phase. Both phases are stable at ambient pressure and temperature below −30°C. At ambient temperature the phases return to the starting phase (α-SeO₂) in a few days. We discuss our findings in relation to a previous report of in-situ measurements at high pressures and ambient temperature.     

Synthesis and structure of Cu3PO4[1,2,4-triazole]2OH with a hybrid layered structure: A new organically templated copper (II) hydroxyphosphate

A new layered copper hydroxyphosphate Cu₃PO₄(1,2,4-triazole)₂OH was synthesized by the mild hydrothermal route and the crystal structure was solved by the single crystal X-ray diffraction method. This compound crystallizes in the monoclinic space group P2₁/a with: a = 10.1456(5) Å, b = 7.8756(4) Å, c = 12.9008(6) Å, β = 111.64(2)°, V = 960.86(8) Å³, Z = 4, D_x = 3.033 g cm^?3. The Cu(II) atoms are embedded in deformed square-pyramidal (Cu1 and Cu3) or octahedral (Cu2) sites made of N and O (or OH) atoms. Both Cu1 and Cu2 polyhedra form dimers connected one to each other, via OH groups, in ribbons which built a bidimensional (001) layer through PO₄ connections. The Cu3 polyhedra built a (001) double-sheet layer through triazol connections. These layers are bridged by triazole and PO₄ groups along the c-direction yielding a lamellar arrangement. Its structural analysis evidences a two-dimensional character for this copper hybrid material which could begin a new series of MOF compounds.     

Ligand-based luminescence in lead-containing complexes: The effect of conjugated organic ligands on fluorescence

The asymmetrically substituted heterocyclic alkyne 5-(pyridin-3-ylethynyl) picolinate (P3PA) was synthesized via a one-pot Sonogashira coupling. After purification, P3PA was reacted with Pb(NO₃)₂ into the two-dimensional coordination polymer Pb(P3PA)₂(H₂O)₂ (1) under hydrothermal conditions. Coordination polymer 1 crystallizes into the monoclinic space group I2/a, with a = 15.5775(10) Å, b = 5.9949(4) Å, c = 24.8380(16) Å, and β = 90.7500(10)°. In addition, the luminescent fluorene-based ligands, fluorene-9-carboxylate (FCA) and fluorenone-2,7-dicarboxylate (FDCA), were incorporated into hybrid materials via coordination to the lead (II) cation. Coordination polymer Pb(FCA)₂ (2) crystallizes in the monoclinic space group P2₁/c (a = 8.0518(9) Å, b = 25.338(3) Å, c = 10.5842(12) Å, β = 94.913(2)°), and forms a 1-D polymeric chain. Coordination polymer Pb₃(FDCA)₃(H₂O)₃ (3) crystallizes in the triclinic space group P1 (a = 6.6990(5) Å, b = 10.1529(7) Å, c = 13.6935(9) Å, α = 81.884(2)°, β = 87.260(2)°, γ = 84.399(2)°), and forms pillared 3-D layers. These three compounds have been identified via single crystal X-ray diffraction and characterized via powder X-ray diffraction, UV–Vis spectroscopy, and fluorescence spectroscopy.     

Crystal structure and thermal analysis of the tetramethylammonium dichromate and trichromate

The structures of the tetramethylammonium dichromate, [(CH₃)₄N]₂Cr₂O₇ and trichromate, [(CH₃)₄N]₂Cr₃O₁₀, were determined from single-crystal X-ray diffraction data. These compounds crystallize in the orthorhombic system (space group Pnma, with Z=4 and a=17.192(1) Å, b=8.55(1) Å, c=10.637(1) Å), for the dichromate and in the monoclinic system (space group P2₁/n, with Z=4 and a=11.366(2) Å, b=8.493(2) Å, c=20.187(4) Å, β=103.98(3)° for the trichromate. The structures consist of discrete dichromate anions (Cr₂O₇)^2– or trichromate anions (Cr₃O₁₀)^2–, respectively, stabilized by quaternary ammonium [(CH₃)₄N]⁺. Phase transitions in [(CH₃)₄N]₂Cr₂O₇ have been evidenced by differential scanning calorimetry as well as a new allotropic variety of [(CH₃)₄N]₂Cr₂O₇ which was characterized by X-ray powder diffraction. It crystallizes in an orthorhombic system with the unit cell parameters a=24.49(1) Å, b=8.85(1) Å, c=8.705(8) Å.     

One-dimensional coordination polymers generated from an oxadiazole-containing N,N′-bipyridine-type ligand and Cu(II) salts

Three new Cu(II) coordination polymers have been prepared using Cu(II) salts in combination with 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L2). The compounds were characterized by single crystal X-ray diffraction, IR spectroscopy, and elemental analysis. In the solid state, all three new polymeric compounds 1–3 (1: monoclinic, P2/c, a=10.0956(11) Å, b=6.8710(7) Å, c=18.6152(19) Å, β=97.270(2)°, V=1280.9(2) ų, Z=2; 2: monoclinic, P2₁/c, a=9.2275(5) Å, b=16.0479(9) Å, c=18.3403(3) Å, β=91.1260(10)°, V=2715.4(3) ų, Z=4; 3: triclinic, P-1, a=6.9932(7) Å, b=11.5777(12) Å, c=12.5291(13) Å, α=109.401(2)°, β=103.922(2)°, γ=95.316(2)°, V=912.06 ų, Z=2) feature novel one-dimensional single or double-sinusoidal chain motifs with different repeat periods, which result from the different conformations adopted by the L2 ligand.     

Hydroflux synthesis and crystal structure of new lanthanide tungstate oxyhydroxides

Single crystals of Na₅Ln(OH)₆WO₄ where Ln = Er, Tm, and Yb were grown out of a NaOH hydroflux. The crystals were characterized by single crystal X-ray diffraction and were found to crystallize in the monoclinic space group I2/a. The lattice parameter ranges for the three structures are a = 11.2024(7) Å–11.2412(6) Å, b = 16.1850(10) Å–16.2220(10) Å, and c = 11.9913(7) Å–12.0323(7) Å while the β angle range is 101.999(2)°–102.025(2)°.     

A novel interpenetrating 2-D brush-like structure: hydrothermal synthesis and crystal structure of [Cu(phen)V4O10]∞ (phen=1,10-phenanthroline)

A novel vanadium oxide, [Cu(phen)V₄O₁₀]_∞ (1), has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR, EPR spectroscopy and thermal analysis. The compound crystallizes in monoclinic structure of P2₁/m with a=7.4169(10) Å, b=10.0460(13) Å, c=11.0845(15) Å, β=102.520(2)°, V=806.27(19) Å³ and Z=2.     

Two new organic–inorganic complexes associating the radical anion ABTS·– and the inorganic cation Ca2+: Ca0.55(ABTS)(H2O)x and Ca5(ABTS)6(H2O)29

The synthesis, crystal structure determination and physical properties of two new charge transfer salts containing the azinobisethylbenzothiazoline (ABTS) anion are described. Electrochemical oxidation in water of the diammonium salt of ABTS in presence of calcium chloride yields black single crystals of two new compounds with different morphologies. The needle-like crystals with Ca_0.55(ABTS)(H₂O)_x formula (x depending on the temperature) belong to the monoclinic symmetry, space group C2/c and cell parameters a=21.568(5), b=14.535(5), c=8.0278(17) Å, β=108.32(3)° at room temperature and a=22.180(4), b=14.288(3), c=8.0823(16) Å, β=108.13(3)°, with a lowering of the symmetry, space group Cc, at 200 K. The plate-shaped crystals formulated as Ca₅(ABTS)₆(H₂O)₂₉ belong also to the monoclinic symmetry with P2₁ space group and cell parameters a=11.222(2), b=37.991(8), c=19.327(4) Å, β=106.37(3)° at 200 K. The structure analysis of the first phase shows a one-dimensional character based on the stacking of organic molecules creating channels in which Ca²⁺ cations and water molecules are located. The second phase can be described as an alternation of organic and inorganic layers corresponding to a bidimensional hybrid network. The magnetic and electrical properties will be discussed.     

New hydrogen-bonded dimeric and polymeric gold(I) complexes of the heterodifunctional ligand Ph2PNHP(O)Ph2

The preparation of several new gold(I) complexes by chloride metathesis of [AuCl(HL)] [HL=Ph₂PNHP(O)Ph₂] with either HL or K[Ph₂P(E)NP(E)Ph₂] (E=S or Se) is described. All compounds were characterised by a combination of ³¹P{¹H}, ¹H and IR spectroscopy, microanalysis and X-ray crystallography. X-ray structural studies reveal that [Au(HL)₂]Cl [monoclinic, space group P2₁/c, a=9.0726(3) Å, b=21.0847(6) Å, c=12.0131(3) Å, β=105.1090(10)°, V=2219 ų, Z=2, final R=3.97] forms a one dimensional polymeric structure in which alternating [Au(HL)₂]⁺ and Cl⁻ ions are linked through intermolecular N–H⋯Cl hydrogen-bonding. In contrast the three-co-ordinate compound [Au{Ph₂P(Se)NP(Se)Ph₂-Se,Se′}(HL)] [monoclinic, space group P2₁/a, a=21.6752(5) Å, b=9.1200(10) Å, c=24.0742(7) Å, β=106.080(2)°, V=4573 ų, Z=4, final R=8.94] forms hydrogen-bonded dimer pairs analogous to that previously observed in non-complexed HL. The X-ray crystal structure of the gold(I) precursor [AuCl(HL)] has also been determined: monoclinic, space group P2₁/c, a=10.217(8) Å, b=23.256(5) Å, c=20.086(5) Å, β=101.15(4)°, V=4683 ų, Z=8, final R=5.2. The X-ray crystal structure reveals intermolecular N–H⋯OP hydrogen-bonding between adjacent [AuCl(HL)] molecules forming infinite chains.     

Phase equilibria in the Ag4SSe–As2Se3 system

The phase diagram of the system Ag₄SSe–As₂Se₃ is studied by means of X-ray diffraction, differential thermal analyses and measurements of the microhardness and the density of the materials. The unit-cell parameters of the intermediate phases 3Ag₄SSe·As₂Se₃ (phase A) and Ag₄SSe·2As₂Se₃ (phase B) are determined as follows for phase A: a=4.495 Å, b=3.990 Å, c=4.042 Å, α=89.05°, β=108.98°, γ=92.93°; for phase B: a=4.463 Å, b=4.136 Å, c=3.752 Å, α=118.60°, β=104.46°, γ=83.14°. The phase 3Ag₄SSe·As₂Se₃ and Ag₄SSe·2As₂Se₃ have a polymorphic transition α?β consequently at 105 and 120°C. The phase A melts incongruently at 390°C and phase B congruently at the same temperature.     

One‐Dimensional Zinc Selenophosphates: A2ZnP2Se6 (A = K,Rb, Cs)

The new compounds A₂ZnP₂Se₆ (A = K, Rb, Cs) were synthesized via molten salt flux syntheses. The crystals feature one‐dimensional ¹/_∞[ZnP₂Se₆]^2– chains charge balanced by alkali metal ions between the chains. K₂ZnP₂Se₆ crystallizes in the monoclinic space group P2₁/c; cell parameters a = 12.537(3) Å, b = 7.2742(14) Å, c = 14.164(3) Å, β = 109.63(3)°, Z = 4, and V = 1216.7(4) ų. Rb₂ZnP₂Se₆ and Cs₂ZnP₂Se₆ are isotypic, crystallizing in the triclinic space group P$\bar{1}$ . Rb₂ZnP₂Se₆ has cell parameters of a = 7.4944(15) Å, b = 7.6013(15) Å, c = 12.729(3) Å, α = 96.57(3)°, β = 105.52(3)°, γ = 110.54(3)°, Z = 2, and V = 636.6(2) ų. Cs₂ZnP₂Se₆ has cell parameters of a = 7.6543(6) Å, b = 7.7006(6) Å, c = 12.7373(11) Å, α = 97.007(7)°, β = 104.335(7)°, γ = 109.241(6)°, Z = 2, and V = 669.54(10) ų.