George L. Schimek

Synthesis of new Group III fluoride–ammonia adducts in supercritical ammonia: structures of AlF3(NH3)2 and InF2(NH2)(NH3)

Abstract The reaction of NH 4 F with AlN and InN in supercritical ammonia at 400°C leads to the formation of two new metal fluoride amine complexes AlF 3 (NH 3 ) 2 ( I ) and InF 2 (NH 2 )(NH 3 ) ( II ). Both compounds were characterized by single-crystal X-ray diffraction. Compound I crystallizes in space group Immm , with Z =2 and unit cell dimensions: a =3.7184(8), b =7.001 (1), c =7.307(2) A, V =190.22(7) A 3 . Compound II crystallizes in the monoclinic space group P 2 1 / n , with Z =4 and unit cell dimensions: a =7.723(3), b =5.394(2), c =8.638(2) A, β =95.52(2)°, V =358.2(2) A 3 . Both are completely new structural types and consist of extended arrays of distorted metal octahedra linked by bridging fluorides. In compound I , all octahedra are corner sharing with linear bridging fluorides. The resultant parallel chains are linked together by NH⋯F hydrogen bonding between terminal fluorides and coordinated amines. In II , there is a combination of distorted edge and corner-sharing octahedra with fluorides acting as edge-bridging groups and amides acting as corner-sharing units. The arrays form layers which are held together by hydrogen bonding.

SYNTHESIS OF ONE DIMENSIONAL TIN SELENIDES IN SUPERCRITICAL AMINES

Abstract Three new crystalline tin selenide salts have been prepared from the reactions of [PPh4]2[Sn(Se43] in supercritical solvents. The starting material pyrolyzes in supercritical acetonitrile to form [PPh4]4[Sn6Se21] (I), and it also reacts with SnSe in supercritical ammonia leading to a mixture of [PPh4]4[Sn3Se11]2 (II). and [PPh4]2[Sn(Se4)(Se6)2] (III). All three compounds have been characterized by single crystal X-ray diffraction. Crystallographic data: for I, C96H90P4Se21Sn6, space group triclinic, P-1, a = 18.763(3), b = 24.600(4), c = 13.137(1) A , α = 102.63(1), β = 93.66(1), γ = 108.72(1)°, V = 5544(1) A 3 , Z = 2, R = 0.0350, R W = 0.0317: for II , C96H80P4Se22Sn6, space group monoclinic P2 1 /c, a = 31.500(4), b = 16.572(3), c = 22.352(3) A , β = 103.53(1)°, V = 11344(3) A 3 , Z = 4, R = 0.0771, R W = 0.0664: for III , C48H40P2Se16Sn, space group monoclinic, C2/c, a = 25.381(2), b = 13.934(4), c = 19.465(3) A , β = 121.587(8)°, V = 5867(2) A 3 , Z = 4, R = 0.0807, R W = 0.0650 . One of the compounds, [PPh4]2[Sn(Se4(Se62], is a molecular cluster while the other two complexes [PPh4]4[Sn3Se11]2 and [PPh4]4[Sn6Se21], are one dimensional tin selenide chains. The structures of the two chains are related and consits of tetrahedral and distorted trigonal bipyramidal tin(IV) centers bridged by Se2−, Se22− and Se32− chains.

Synthesis, structure, and magnetic properties of two quasi-low-dimensional antiferromagnets, NaMnAsO4 and β-NaCuPO4 ☆

Abstract Crystals of NaMnAsO4 (1) and β-NaCuPO4 (2) were grown by conventional high-temperature, solid-state methods in molten salt media. The compounds were characterized by single crystal X-ray diffraction and magnetic susceptibility measurements. Compound 1 crystallizes in an orthorhombic lattice with a=10.853(3) A, b=6.383(2) A, c=5.157(2) A, and V=357.2(2) A3; Pnma (No. 62); Z=4, while 2 crystallizes in a monoclinic lattice with a=6.943(1) A, b=8.848(1) A, c=5.013(1) A, β=97.25(1)° and V=305.53(9) A3; P21/n (No. 14); Z=4. The new sodium manganese(II) arsenate is isostructural with LiMnAsO4, which contains single layers of (100) perovskite sheet made of distorted MnO6 octahedra. Sodium copper(II) phosphate adopts a known β-form that possesses linear chains of edge-shared CuO6 octahedra depicting a [4+2] Jahn–Teller distortion. These structurally isolated magnetic layers and chains are incorporated into a three-dimensional lattice via the linkage by closed-shell, non-magnetic oxy anions. Magnetic susceptibility measurements reveal that the title compounds are antiferromagnetic with the negative Weiss constants θ=−76.99 K (1) and −33.85 K (2). At low-temperatures, magnetic susceptibility data feature a field-induced antiferromagnetic-to-ferromagnetic transition. The field dependence studies further indicate that these phenomena could be attributed to metamagnetism and a spin-flop transition, respectively. The current work in the exploratory synthesis of quasi-low-dimensional TM-based oxy compounds gives a new perspective to the continued investigation of experimental and theoretical developments of magnetic models.

Main Group Metal Halide Complexes with Sterically Hindered Thioureas: Part XVII. The Crystal and Molecular Structures of Two New Tellurium Chloride Complexes with 1,3-dimethyl-2(3H)-imidazolethione

Abstract In an attempt to determine the crystal and molecular structure of previously reported [TeCl2(dmit)4] (1) [dmit=1,3-dimethyl-2(3H)-imidazolethione], recrystallization in hot acetonitrile yielded two new complexes, [TeCl2(dmit)2] (2) and [TeCl4(dmit)2] (3) as determined by X-ray crystallography. The structure of 2 consists of a cis-substituted square planar geometry with the thione rings both oriented on the same side of the TeS2Cl2 plane. The complex undergoes very slow decomposition in air. The structure of 3 is a near-octahedral arrangement with the thione ligands trans to each other

The coordination chemistry of cationic main group clusters: syntheses and structures of [Fe3(Se2)2(CO)10]2+ and [Fe4(Se2)3(CO)12]2+☆

The reactions of the polysulfur and selenium cationic clusters S82+ and Se82+ with various iron carbonyls were investigated. Several new chalcogen containing iron carbonyl cluster cations were isolated, depending on the nature of the counteranion. In the presence of SbF6− as a counterion, the cluster [Fe3(E2)2(CO)10] [SbF6]2·SO2 (E = S, Se) could be isolated from the reaction of E82+ and excess iron carbonyl. The cluster is a picnic-basket shaped molecule of two iron centers linked by two Se2 groups, with the whole fragment capped by an Fe(CO)4 group. Crystallographic data for C10O12Fe3Se4Sb2F12S (I): space group monoclinic P21/c, a = 11.810(9), b = 24.023(6), c = 10.853(7) A, β = 107.15(5)°, V = 2942(3) A3, Z = 4, R = 0.0426, Rw = 0.0503. When Sb2F11− is present as the counterion, or Se4[Sb2F11]2 is used as the cluster cation source, a different cluster can be isolated, which has the formula [Fe4(Se2)3(CO)12] [SbF6]2·3SO2. The dication contains two Fe2Se2 fragments bridged by an Se2 group. Crystallographic data for C12O18Fe4Se6Sb2F12S3 (III): space group triclinic P1, a = 10.941(4), b = 18.400(9), c = 10.253(4) A, α = 93.10(4), β = 103.74(3), γ = 93.98(3)°, V = 1995(1) A3, Z = 2, R = 0.0328, Rw = 0.0325. The CO stretches in the IR spectrum all show a large shift to higher wavenumbers, suggesting almost no τ backbonding from the metals. This also correlates with the observed bond distances. All the compounds are extremely sensitive to air and water, and readily lose SO2 when removed from the solvent. Thus all the crystals were handled at −100°C. The clusters seem to be either insoluble or unstable in all solvents investigated.

The Chemistry of Anionic Antimony Selenides

Abstract The reaction of [HFe(CO)4]− with various binary antimony selenides was investigated. In the presence of Sb2Se3 the organometallic anion acts as a reducing agent leading to formation of [Sb4Se6]2- which has a crown shaped geometry with a transannular Sb-Sb bond. Reaction with Sb2Se5 leads to incorporation of iron carbonyl with formation of a dimer of formula [Fe2(CO)4(SbSe4)2]2-. The cluster contains two Fe(CO)2 fragments bridged by SbSe4 3- units. The main group anions are not tetrathiometallates, but rather a trivalent Sb bound to two selenides and a diselenide. Both compounds were structurally characterized as their [PPh4]+ salts. Crystal data for [PPh4]2[Sb4Se6], triclinic, P-1, a = 10.124(2)A, b = 14.670(2)A, c = 17.352(2)A, α = 96.42(2)˚, β = 95.78(2)˚, γ = 97.09(2)˚, V = 2524.2(7)A3, Z = 2, R = 0.0377, Rw = 0.0465; crystal data for [PPh4]2[Fe2(CO)4(SbSe4)2], monoclinic, P21/n, a = 15.552(5)A, b = 110.279(3)A, c = 18.159(6)A, β = 101.72(3)˚, V = 2819(1)A3, Z = 2, R = 0.0372, Rw = 0.0395.

Synthesis and characterization of MAgSe4 (M=Rb, Cs)

Syntheses of the title compounds were achieved from supercritical amines. The single crystal X-ray characterization of both MAgSe4 (M=Rb, Cs) members indicates that they are isostructural. The structure is built from five membered AgSe4 rings that are stitched together through tetrahedrally coordinated Ag(I) ions to form one dimensional chains running parallel to the a-axis. These chains are separated from each other by the alkali metal cations. Crystal data: orthorhombic, P212121, Z = 4. RbAgSe4: a = 5.809(2), b = 8.927(3), c = 13.435(4) Å, U = 698.2(4) Å3, and Dc = 4.851 g/cm3. CsAgSe4: a = 5.855(2), b = 9.090(3), c = 13.885(4) Å, U = 739.0(4) Å3, and Dc = 5.003 g/cm3. The anionic chain found in the title compounds has been observed previously, and comparisons among these phases show that the silver ion coordination in the chain varies as a function of cation size. Both the title compounds are valence precise and optical diffuse reflectance studies show that they are semiconductors with moderately large band gaps.

Hydrothermal synthesis and structural determination of a three-dimensional microporous iron(III)phosphate: [H3N(CH2)4NH3]3[Fe8(HPO4)12(PO4)2(H2O)6]

Abstract A new microporous iron (III) phosphate, [H 3 N(CH 2 ) 4 NH 3 ] 3 [Fe 8 (HPO 4 ) 12 (PO 4 ) 2 (H 2 O) 6 ], has been prepared using low temperature hydrothermal methods and characterized by single-crystal X-ray diffraction, EDAX, infrared spectroscopy, thermogravimetric analysis and bond valence sums. The title compound crystallizes as light pink hexagonal-shaped tabs in the centrosymmetric hexagonal space group 3¯ (No.147) with a = b = 13.495(2) A, c = 9.396(2) A, V = 1481.9(4) A 3 and Z = 4 with R/R w = 0.044/0.048. The compound exhibits a complicated three-dimensional microporous structure with quaternary ammonium ions acting as a template for the framework. It is similar to previously reported [HN(CH 2 CH 2 ) 3 NH] 3 [Fe 8 (HPO 4 ) 12 (PO 4 ) 2 (H 2 O) 6 ].

Synthesis and structural characterization of CsAg5Se3 and RbAg3Te2

The syntheses and structure determinations of CsAg5Se3 (I) and RbAg3Te2 (II) are reported. Both compounds were prepared by using supercritical ethylenediamine at 300°C for 6 days reacting alkali polychalcogenides with silver. For the compound I; tetragonal space group P42/mnm, a = 14.083(2)Å, c = 4.410(2)Å, V = 874.5(4)Å3, Z = 4, D = 6.905 Mg/m3, MoKα radiation, λ = 0.71073, μ = 27.493 mm−1, F(000) = 1568, R = 0.022, Rw = 0.026 for 472 independent reflection. For compound II; monoclinic space group C2/m, a = 17.546(2)Å, b = 4.617(2)Å, c = 9.165(2)Å, β = 113.04(2)°, V = 683.31(12)Å3, Z = 2, D = 6.457 Mg/m3, MoKα radiation, λ = 0.71073, μ = 23.825 mm−1, F(000) = 1128, R = 0.019, Rw = 0.027 for 690 independent reflection.

Dichlorobis[1,3-dimethylimidazole-2(3H)selone-Se]cobalt(II)

The crystal structure of the title compound, [CoCl2(C5H8N2Se)2], shows a discrete molecular structure with tetrahedral geometry around the cobalt ion. The mean Co—Cl and Co—Se distances are 2.277 (3) and 2.456 (3) A, respectively. Bond angles around the Co atom range from 101.1 (1) to 120.0 (1)°. Ring distances and angles in the ligand compare favorably with the literature values of analogous compounds, and show significant increases from values observed in the uncoordinated selone. However, the mean C—Se bond distance of 1.88 (2) A shows no significant difference from the free ligand. Other corresponding bond distances and angles show no significant differences between the free and coordinated ligands.