Showing papers in "Zeitschrift für anorganische und allgemeine Chemie in 2008"

A Cobalt(II)‐containing Metal‐Organic Framework Showing Catalytic Activity in Oxidation Reactions

Abstract: A metal-organic framework (MOF) containing redox active CoII atoms, [CoII(BPB)]·3DMF (1), has been prepared from the solvothermal reaction of CoII nitrate and 1,4-bis(4′-pyrazolyl)benzene (H2-BPB) in dimethylformamide (DMF). Compound 1 constitutes a porous coordination framework that is built up by interconnecting 1D CoII polymer chains with (BPB)2− ligands. The thermal stability of 1 was investigated by thermogravimetric (TG) analysis and variable-temperature X-ray powder diffraction (VTXRPD), which indicate that the framework of 1 is stable upon removal of solvent molecules. The argon adsorption isotherm of 1 at 77 K indicates a porous structure with a BET surface area of 1207 m2/g. As a test reaction for catalytic activity of 1, the oxidation of cyclohexene was examined employing tert-butyl hydroperoxide as oxidant. The maximum substrate conversion achieved after 12 h was 62 % with an estimated turn-over number (TON) of 44 based on the number of converted substrate molecules (cyclohexene) per CoII atom.

5-Azido-1H-tetrazole – Improved Synthesis, Crystal Structure and Sensitivity Data

Abstract: Due to the highly explosive nature of 5-azido-1H-tetrazole (1), its characterization has not been fully described in the literature yet. In addition, the previously published crystal structure was of low quality, and therefore the position of the hydrogen atom was not certain. In order to resolve these problems, 1 was prepared in an improved synthesis, and the results of the subsequent detailed reinvestigation and characterization are given. The reaction of cyanogen bromide with two equivalents of sodium azide at low temperatures yielded sodium 5-azidotetrazolate, which was protonated using dilute hydrochloric acid. The product 1 was isolated and characterized using multinuclear (1H, 13C, 15N) NMR spectroscopy, vibrational (IR and Raman) spectroscopy and mass spectrometry. The structure of 1 in the crystalline state was determined using low-temperature single-crystal X-ray diffraction. In addition, the optimized gas-phase structures of the 5-azido-1H-tetrazole and 5-azido-2H-tetrazole isomers were calculated (MP2/aug-cc-pVDZ) and the electronic energies were compared. The heat of formation of 1 was calculated and several detonation parameters were estimated using the EXPLO5 software. The thermal behavior was investigated using DSC (differential scanning calorimetry) and the sensitivity of this highly energetic material was tested using the BAM drophammer, ESD and friction tester. X-ray: 1: monoclinic, P21/c, a = 13.265(2) A, b = 4.9693(6) A, c =16.304(3) A, β = 127.04(1)°, V = 857.9(3) A3, Z = 8, ρ = 1.720 g cm−3.

Salts of 1H‐Tetrazole – Synthesis, Characterization and Properties

Abstract: The most facile route for the formation of 1H-Tetrazole (1, TZ) is the reaction of sodium azide with ammonium chloride and orthoethyl formate in glacial acetic acid. 1 was deprotonated using alkali hydroxides and carbonates yielding the corresponding metal salts LiTZ (4), NaTZ·H2O (5), KTZ (6), RbTZ (7) and CsTZ (8). The nitrogen rich salts NH4TZ·H2O (2) and N2H5TZ (3) were synthesized by the reaction of 1H-tetrazole with aqueous NH3 and N2H4 solutions, respectively. In addition, Sr(TZ)2·5H2O (9) was obtained by deprotonation of 1 using Sr(OH)2·8H2O and its use as possible energetic ingredient in modern pyrotechnic compositions as a red component was investigated. All compounds were characterized using vibrational (IR and Raman) spectroscopy, multinuclear (1H, 7Li, 13C, 14N, 15N) NMR spectroscopy and elemental analysis. The structures in the crystalline state of compounds 2, 3, 4, 5, 6, 7, 8 and 9 were determined using low temperature X-ray diffraction and a detailed description is given in this work. The physico-chemical properties of all compounds were investigated using DSC (differential scanning calorimetry) and the heats of formation were calculated using heats of combustion obtained by bomb calorimetry. Since tetrazoles often are energetic materials, the sensitivities of compounds 1–9 were tested using the BAM drophammer and friction tester. Crystal Data: 2: monoclinic, P21/n, a = 7.211(1), b = 4.0108(8), c = 17.991(4) A, β = 91.97(3)°, V = 520.0(2) A3, Z = 4, ρ = 1.343 g cm−3; 3: orthorhombic, Ccca, a = 6.763(1), b = 17.7510(4), c = 16.3160(8) A, V = 1958.7(3) A3, Z = 16, ρ = 1.385 g cm−3; 4: orthorhombic, C2221, a = 13.499(2), b = 14.389(3), c = 14.125(3) A, V = 2743.6(9) A3, Z = 8, ρ = 1.472 g cm−3; 5: orthorhombic, Pmma, a = 6.400(2), b = 5.837(1), c = 5.608(2) A, V = 209.51(9) A3, Z = 2, ρ = 1.745 g cm−3; 6: hexagonal, , a = 14.0037(2), b = 14.0037(2), c = 10.7285(2) A, V = 1822.03(5) A3, Z = 6, ρ = 1.774 g cm−3; 7: hexagonal, P63/m, a = 8.260(2), b = 8.260(2), c = 11.009(3) A, V = 650.5(3) A3, Z = 6, ρ = 2.367 g cm−3; 8: orthorhombic, Pbca, a = 7.3406(8), b = 9.610(1), c = 12.199(1) A, V = 860.5(2) A3, Z = 8, ρ = 3.118 g cm−3; 9: orthorhombic, Pnnm, a = 11.314(2), b = 13.876(3), c = 7.121(1) A, V = 1117.9(4) A3, Z = 2, ρ = 1.877 g cm−3.

Continuous Preparation of Calcite, Aragonite and Vaterite, and of Magnesium-Substituted Amorphous Calcium Carbonate (Mg-ACC)†

Abstract: The three water-free calcium carbonate polymorphs calcite, aragonite and vaterite were prepared from aqueous solutions without additives using standard laboratory equipment in a continuous process. Variation parameters were the way of mixing, the solution concentrations, and the reactor residence time. The samples were crystallographically and chemically pure, but a thorough elemental analysis revealed the presence of small amounts of sodium carbonate which was not detectable by X-ray powder diffraction. The continuous process avoids the inherent variability of batch syntheses. By adapting the crystallization parameters, magnesium-substituted amorphous calcium carbonate (molar ratio of Mg:Ca of 1:2.68) was prepared in this continuous process.

Solvothermal Syntheses, Crystal Structures and Selected Optical Properties of [M(C8N5H23)]2Sn2S6 (M = Co, Fe, Ni; C8N5H23 = tetraethylenepentamine)†

Abstract: Three new thiostannates [Co(C8N5H23)]2Sn2S6 (I), [Fe(C8N5H23)]2Sn2S6 (II) and [Ni(C8N5H23)]2Sn2S6 (III) were synthesized under solvothermal conditions. In all compounds the [Sn2S6]4− anion acts as a bidentate or μ2 ligand bridging two symmetry related [M(C8N5H23)]2+ cations. Despite the identical building units only compounds I and II are isostructural crystallizing in the tetragonal space group I41/a, whereas compound III crystallizes in space group P21/n. A detailed analysis of the intermolecular interactions reveals remarkable differences between I/II and III which may be responsible for the crystallization in different symmetries and space groups. The slightly different bonding situations in the [Sn2S6]4− anion in I/II and III are reflected in the Raman spectra. For all three compounds the UV/Vis spectra show d-d transitions energetically below the absorption edge.

Neues aus der Chemie des Berylliums

Abstract: Recent Advances in the Chemistry of Beryllium A review of recent results in coordination chemistry of beryllium halides is given. In accordance with the editors' objective, this Research Report is not a complete review of the literature in this field, but the important literature close to it is considered. The following subjects are presented: (i) Syntheses and structural characterizations of tetraphenylphosphonium salts of [BeCl4]2−, [Be2Cl6]2−, and the unique [Be2F6]2− ion, which are soluble in organic solvents like dichloromethane or acetonitrile. (Ph4P)2[Be2F6]·2CH3CN is also extensively studied by IR spectroscopy and quantum chemical calculations (DFT). (ii) Application of (Ph4)2[Be2Cl6] to prepare donor acceptor complexes with N-donor ligands D to give complexes [BeCl3(D)]− which are isoelectronical with the corresponding boron compounds [BCl3(D)], including quantum chemical calculations. (iii) Molecular complexes of the type [BeCl2(D)2] with D = phosphorane imines HNPR3 or Me3SiNPR3. (iv) Phosphoraneiminato complexes of beryllium, among these the first example [BeCl(μ-NPEt3)]4 with a Be4N4 heterocubane skeleton. (v) Azido complexes of several types, including the unique examples with adamantane-like structure [Be4X4(μ-N3)6]2− with X = Cl, Br. (vi) Monocationic complexes [BeCl(12-crown-4)]+[SbCl4]− and [BeCl(PMDETA)]+Cl− (PMDETA = pentamethyl-diethylenetriamine). (vii) Dicationic complexes with O-donor ligands H2O and OSMe2. [Be(OH2)4]Cl2, [Be(OSMe2)4]Cl2, and mixed ligand complexes like [Be(OH2)2(OSMe2)2]Cl2. (viii) Molecular and anionic oxo-complexes, particularly with μ-OSiMe3 groups, among these the tetramethyl-trioxosilanato complex (Ph4P)2[Be4(μ-Cl)2Cl4(OSiMe2OSiMe2O)2].

Hydrogen-bonding Stabilization in Energetic Perchlorate Salts: 5-Amino-1H-tetrazolium Perchlorate and its Adduct with 5-Amino-1H-tetrazole

Abstract: Protonation of 5-amino-1H-tetrazole (5-At) with concentrated perchloric acid in water rendered 5-amino-1H-tetrazolium perchlorate (1), in good yield and purity, or an adduct of 1 with 5-At (2) depending on the experimental conditions used. 1 was more conveniently prepared by metathesis of 5-amino-1H-tetrazolium bromide (3) with anhydrous silver perchlorate in alcoholic solution. Both perchlorate salts were characterized by NMR, Raman and IR spectroscopy, differential scanning calorimetry, mass spectrometry and elemental analysis. Additionally, the crystal structures of 1 and 2 were determined by X-ray diffraction techniques. Both salts crystallize in monoclinic cells in the space group P21/n (1: a = 5.3691(6), b = 7.8470(6), c = 15.2770(13) A, β = 91.381(8)°, V = 643.45(10) A3, Z = 4, o = 1.915 g cm–3, R1 = 0.0403 (F > 4σ(F)), wR2 (all data) = 0.0977 and 2: a = 5.2615(1), b = 8.5311(2), c = 21.4870(4) A, β = 96.127(1)°, V = 958.96(3) A3, Z = 4, o = 1.874 g cm–3, R1 = 0.0330 (F > 4σ(F)), wR2 (all data) = 0.0890). Lastly, the energetic properties of 1 and 2 were assessed. With an impact (i) and friction (f) sensitivitiy of 1.5 J and 8 N, respectively, and a sensitivity of 0.1 J against electrical discharge (ESD) perchlorate 1 is a powerful primary explosive, whereas the presence of a second tetrazole ring in 2 makes it a very stable compound (i = 22 J, f = 260 N, ESD = 0.4 J).

Synthesis, Crystal Structures, and Urease Inhibitory Activities of Three Novel Thiocyanato‐bridged Polynuclear Schiff Base Cadmium(II) Complexes

Abstract: Three novel thiocyanato-bridged polynuclear cadmium(II) complexes, [Cd(HL1)(NCS)2(μ1,3-NCS)]n (1), [CdL2(μ1,3-NCS)2]n (2), and [CdL3(μ1,3-NCS)2]n (3) (L1 = N-methyl-N′-(1-pyridin-2-ylmethylidene)ethane-1,2-diamine, L2 = 2-(cyclopropyliminomethyl)-6-methoxyphenol, L3 = 2-(cyclopentyliminomethyl)-6-methoxyphenol), have been synthesized and structurally characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. Each cadmium(II) atom in the complexes is in an octahedral coordination. The urease inhibitory activities of the complexes were evaluated. All of them showed potent inhibitions against jack bean urease.

The Synthesis of (η3-C3H5)Pd{Si[N(tBu)CH]2}Cl and the Catalytic Property for Heck Reaction

Abstract: Treatment of N-heterocyclic silylene Si[N(tBu)CH]2 (1) and [(η3-C3H5)PdCl]2 in toluene led to the formation of the mononuclear complex (η3-C3H5)Pd{Si[N(tBu)CH]2}Cl (3), the silicon analogue to N-heterocyclic carbene complex (η3-C3H5)Pd{C[N(tBu)CH]2}Cl (2) Complex 3 was characterized with 1H NMR and 13C NMR Investigation shows that (η3-C3H5)Pd{Si[N(tBu)CH]2}Cl is an active catalyst for Heck coupling reaction of styrene with aryl bromides

On the Flexibility of Thioantimonate Networks: Solvothermal Syntheses and Crystal Structures of Six New Thioantimonates(III) with the [Sb4S7]2− Anion

Abstract: Six new thioantimonates(III) with the [Sb4S7]2− anion were obtained under solvothermal conditions with in-situ formed transition metal complexes as structure directors. In the two isostructural compounds [Fe(dien)2]Sb4S7·H2O (1) and [Co(dien)2]Sb4S7·0.5 H2O (2) (dien = diethylenetriamine; space group: P21/c) the layered [Sb4S7]2− anion is characterized by Sb8S8 rings with a diameter of about 9.6·7.6A. The cation complexes are located above and below the pores of the rings. Despite the larger size of the cation complex the network topology of the third thioantimonate [Ni(dien)(tren)]Sb4S7 (3) (tren = tris(2-aminoethyl)amine; space group: P21/n) is similar to that of the first two compounds. In the isostructural thioantimonates [M(trien)]Sb4S7 (M = Zn (4); M = Mn (5); trien = triethylenetetramine; space group: ) the M2+ ions are fivefold coordinated by four N atoms of the amine molecule and by one S atom of the thioantimonate anion forming a MN4S trigonal bipyramid. Sb8S16 building blocks are the central structural motifs of the anion. Two of the terminal S atoms at the periphery of the Sb8S16 units are bound to M2+ ions and the four remaining terminal S atoms connect adjacent Sb8S16 groups into the final [Sb4S7]2− chain. [Ni(tren)]Sb4S7 (6) (space group: ) contains a one-dimensional anionic chain. The Ni2+ ion has two bonds to the [Sb4S7]2− anion which is a unique feature in the thioantimonate(III) chemistry. The NiN4S2 octahedron is severly distorted with one very long Ni-S bond of 2.782(2) A. In all compounds several short S···H distances indicate hydrogen bonding interactions.

Synthesis and Structures of Dimanganese(II) Complexes with Spirotricyclic [Mn(μ‐Ge2Se7)Mn] and [Mn(μ‐Sn2Se6)Mn] Cores

Abstract: Solvothermal reaction of [MnCl2(cyclam)]Cl with GeSe2 at a 1:1 molar ratio in CH3OH/H2O (1/1) at 150 °C affords the dimanganese(II) complex [{Mn(cyclam)}2(μ-Ge2Se7)]·CH3OH·1.5H2O (1) with a spirotricyclic [Mn(μ-Ge2Se7)Mn] core. The strained four-membered Mn-Set-Ge-Set′ rings (Set = terminal Se atom) exhibit long Mn-Set distances in the range 2.725(2)–2.745(2) A and narrow average Set-Mn-Set′ angles of 85.87(4)°. The solvothermal reaction of [MnCl2(cyclam)]Cl with SnSe and Se leads to formation of the analogous complex [{Mn(cyclam)}2(μ-Sn2Se6.15)] (2), in which bridging [Sn2Se6]4− and [Sn2Se7]4− ligands are disordered at a ratio of 85:15. Employment of [MnCl2(terpy)] under similar conditions generates two complexes of the formula [{Mn(terpy)}2(μ-Sn2Se6)] 3 and 4, of which the former also contains a spirotricyclic core, whereas the Set atoms of the latter coordinate symmetry-related MnII atoms in a 1-D polymer. The Mn-Set bond distances of 2.584(1) and 2.549(1) A in the resulting chair-shaped eight-membered rings of 4 are much shorter than in 1 and 2.

The Metallic Zintl Phase Ba3Si4 - Synthesis, Crystal Structure, Chemical Bonding, and Physical Properties

Abstract: The Zintl phase Ba3Si4 has been synthesized from the elements at 1273 K as a single phase. No homogeneity range has been found. The compound decomposes peritectically at 1307(5) K to BaSi2 and melt. The butterfly-shaped Si46− Zintl anion in the crystal structure of Ba3Si4 (Pearson symbol tP28, space group P42/mnm, a = 8.5233(3) A, c = 11.8322(6) A) shows only slightly different Si-Si bond lengths of d(Si–Si) = 2.4183(6) A (1×) and 2.4254(3) A (4×). The compound is diamagnetic with χ ≈ −50 × 10−6 cm3 mol−1. DC resistivity measurements show a high electrical resistivity (ρ(300 K) ≈ 1.2 × 10−3 Ω m) with positive temperature gradient dρ/dT. The temperature dependence of the isotropic signal shift and the spin-lattice relaxation times in 29Si NMR spectroscopy confirms the metallic behavior. The experimental results are in accordance with the calculated electronic band structure, which indicates a metal with a low density of states at the Fermi level. The electron localization function (ELF) is used for analysis of chemical bonding. The reaction of solid Ba3Si4 with gaseous HCl leads to the oxidation of the Si46− Zintl anion and yields nanoporous silicon.

Effect of Heavy-Atom (Br) at the Phenyl Rings of Schiff-Base Ligands on the NIR Luminescence of their Bimetallic Zn-Nd Complexes

Abstract: Two heterobimetallic Zn-Nd phenylene-bridged Schiff-base ligands complexes [ZnNdL1(Py)(NO3)3] (1) and [ZnL2Nd(Py)(NO3)3]·MeCN (2) (Py = pyridine, H2L1 = N,N′-bis- (3-methoxy-salicylidene)phenylene-1,2-diamine, H2L2= N,N′-bis-5-bromo-3-methoxy-salicylidene)phenylene-1,2-diamine) were obtained. Both 1 and 2 were structurally characterized by X-ray crystallography, and their near-infrared (NIR) luminescent properties were determined. For the two complexes, the occupation of pyridine at the axial position of 3d Zn2+ ions could effectively prevent luminescent quenching arising from OH-, NH- or CH oscillators of the solvates around the 4f Nd3+ ions, and the heavy-atom (Br) effect of the Schiff-base ligands on their NIR luminescent properties is also discussed.

Synthesis of Heteroleptic Cerium(IV) Complexes Using a Heptadentate (N4O3) Tripodale Schiff‐base Ligand

Abstract: The Cerium(IV) complexes [{N[CH2CH2N=CH(2-O-3,5-tBu2C6H2)]3}CeCl] (1) and [{N[CH2CH2N=CH(2-O-3,5-tBu2C6H2)]3}Ce(NO3)] (2) were derived from the condensation of tris(2-aminoethyl)amine and 3,5-di-tert-butylsalicylaldehyde and the appropriate Ce starting material CeCl3(H2O)6 and (NH4)2[Ce(NO3)6], respectively. Single crystal X-ray diffraction studies reveal monomeric complexes.

The Oxidation of Metals with Liebig Acids

Abstract: In Liebig's definition, an acid is a compound which contains one or more hydrogen atoms which may be substituted by metal atoms. Hence, reactions of Liebig acids in substance, excluding water or any other solvent, with non-noble metals yield salts and release hydrogen. In this sense, not only the classical mineral acids such as sulfuric or nitric acid, respectively, are Liebig acids. Rather, there is a large variety of organic compounds with, for example, HO- or HN-functions with acid constants that allow for substitution of the hydrogen atoms by a metal atom. Simple covalent hydrides like water and ammonia or even methane may also act as Liebig acids with conditions properly chosen. The ammonium ion, (NH4)+, represents a special case as it is available in a large variety of salts and may react as an acid/oxidant or as a (base)/reductant and is also a pseudo alkali-metal cation. The versatility of the ammonium ion is reviewed with special emphasis to its ability to function as a Liebig acid, i.e., reactions of, especially, ammonium halides with non-noble metals.

Carbid-verbrückte Komplexe [HB(pz)3(OC)2Mo≡C-Pt(PPh3)2Br], [(TPP)Fe≡C-M(CO)4-M(CO)5] (M = Mn, Re), [(TPP)Fe=C=Cr(CO)5] und (TPP)Fe=C=Fe(CO)4] (pz = 3,5-dimethylpyrazol-1-yl; TPP = Tetra-phenylporphyrinat) aus Halogeno-Carbin und -Carben-Komplexen†

Abstract: Carbide Bridged Complexes [HB(pz)3(OC)2Mo≡C-Pt(PPh3)2Br], [(TPP)Fe≡C-M(CO)4-M(CO)5] (M = Mn, Re), [(TPP)Fe=C=Cr(CO)5], (TPP)Fe=C=Fe(CO)4] (pz = 3,5-dimethylpyrazol-1-yl; TPP = Tetraphenylporphyrinate) from Halogeno-Carbyne and -Carbene Complexes The reaction of the bromocarbyne complex [HB(pz)3(OC)2Mo≡C-Br] with [(Ph3P)2Pt(η2-C2H4)] at room temperature affords the dimetallapropene complex. At higher temperature the isomeric carbide bridged complex [HB(pz)3(OC)2Mo≡C-Pt(PPh3)2Br] is formed. From the tetraphenylporphyrinato-dichlorocarbene–iron complexes [(TPP)Fe=CCl2] with the carbonyl metallates Na[Re(CO)5], Na[Mn(CO)5], Na2[Cr(CO)5] and Na2[Fe(CO)4] the carbide bridged complexes [(TPP)Fe≡C-M(CO)4-M(CO)5] (M = Mn, Re), [(TPP)Fe=C=Cr(CO)5] and [(TPP)Fe=C=Fe(CO)4] have been obtained. Instead of TPP also tetrakis(p-methoxyphenyl)porphyrinate and tetrakis(p-cyanophenyl)porphyrinate have been used.

Dinuclear Manganese(II) Complexes with Bridging Selenidodiarsenate Anions [As2Se4]4−, [As2Se5]4− and [As2Se6]2−

Abstract: Solvothermal reaction of [MnCl2(amine)] (amine = terpy and tren) with elemental As and Se at a 1:1:2 molar ratio in H2O/tren (10:1) affords the dimanganese(II) complexes [{Mn(terpy)}2(μ-As2Se4)] (1) and [{Mn(tren)}2(μ-As2Se5)] (2) respectively. The tetradentate [As2Se4]4− bridging ligands in 1 contain a central As–As bond and exhibit approximately C2h symmetry. Pairs of gauche sited Se atoms participate in five-membered As2Se2Mn chelate rings. In contrast, two AsSe3 pyramids share a common corner in the [As2Se5]4− ligands of 2 and each coordinates an [Mn(tren)]2+ fragment through a single terminal Se atom. Such dinuclear complexes are linked into tetranuclear moieties through weak Se···Mn interactions of length 3.026(3) A involving one of these terminal Se atoms. At a 1:3:6 molar ratio, solvothermal reaction of [MnCl2(tren)] with As and Se leads to formation of a second dinuclear complex [{Mn(tren)}2(μ-As2Se6)2] (3), which contains two bridging bidentate [As2Se6]2− ligands. These are cyclic with an As2Se4 ring and can be regarded as being derived from [As2Se5]4− anions by formation of two Se-Se bonds to an additional Se atom.

Magnetic, Optical, and Electronic Properties of the Phosphide Oxides REZnPO (RE = Y, La–Nd, Sm, Gd, Dy, Ho)

Abstract: Well-shaped yellow to red transparent single crystals of the phosphide oxides REZnPO (RE = Y, La–Nd, Sm, Gd, Dy, Ho) were synthesized from the elements and ZnO in NaCl/KCl fluxes in sealed silica ampoules. Four structures (NdZnPO type, R3m) were refined from single crystal X-ray diffractometer data: a = 388.5(2), c = 3032(1) pm, wR2 = 0.0380, 360 F2 values for YZnPO, a = 394.6(2), c = 3071(1) pm, wR2 = 0.0587, 226 F2 values for SmZnPO, a = 392.2(2), c = 3056(1) pm, wR2 = 0.0262, 462 F2 values for GdZnPO, and a = 389.33(6), c = 3030.5(4) pm, wR2 = 0.0453, 217 F2 values for DyZnPO each with 14 variables per refinement. The structures are composed of alternate stacks of (RE3+O2−) and (Zn2+P3−) layers with covalent RE–O and ZnP bonding within and weak ionic bonding between the layers. The zinc and oxygen atoms have slightly distorted tetrahedral coordination by atoms of phosphorus and the rare earth element, respectively. According to the electron precise formulation RE3+Zn2+P3−O2−, these pnictide oxides are transparent in visible light. Susceptibility measurements on β-CeZnPO, β-PrZnPO, and GdZnPO reveal Curie-Weiss paramagnetism with experimental magnetic moments of 2.31, 3.60, and 7.72 μB/RE atoms, respectively. β-CeZnPO and β-PrZnPO show antiferromagnetic order with Neel temperatures of 7.4 (Ce) and 2.2 (Pr) K. GdZnPO shows no magnetic ordering down to 2 K. Single crystal absorption spectra measured for REZnPO (RE = Y, La, Pr, Nd, Sm, Dy) in the NIR-Vis region reveal unexpected variations for the optical band gap of these phosphide oxides. For RE = Pr, Nd, Sm, Dy, Ho f-f electronic transitions with nicely resolved ligand-field splittings are observed in the range 6000–20000 cm−1. DFT band structure calculations show similarity between the valence bands of tetragonal and rhombohedral REZnPO as they possess mainly P-3p character. In both cases, the conduction bands have mainly Zn-4s character, but a significant contribution of RE-5d occurs in rhombohedral REZnPO, which is responsible for a smaller optical band gap for the latter compounds. Variations of the energy gaps of tetragonal REZnPO can be explained by hybridization of Zn-4s + RE-5d + RE-4f orbitals for the conduction band. DFT volume optimizations of α- and β-PrZnPO show β-PrZnPO to be more stable by 10.7 kJ mol−1.

Encapsulation of Triphenylene Derivatives in the Hexanuclear Arene Ruthenium Metallo-Prismatic Cage [Ru6(p-PriC6H4Me)6(tpt)2(dhbq)3]6+ (tpt = 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine, dhbq = 2,5-dihydroxy-1,4-benzoquinonato)

Abstract: A large cationic triangular metallo-prism, [Ru6(p-PriC6H4Me)6(tpt)2(dhbq)3]6+ (1)6+, incorporating p-cymene ruthenium building blocks, bridged by 2,5-dihydroxy-1,4-benzoquinonato (dhbq) ligands, and connected by two 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine (tpt) subunits, allows the permanent encapsulation of the triphenylene derivatives hexahydroxytriphenylene, C18H6(OH)6 and hexamethoxytriphenylene, C18H6(OMe)6. These two cationic carceplex systems [C18H6(OH)6⊂1]6+ and [C18H6(OMe)6⊂1]6+ have been isolated as their triflate salts. The molecular structure of these systems has been established by one-dimensional 1H ROESY NMR experiments as well as by the single-crystal structure analysis of [C18H6(OMe)6⊂1][O3SCF3]6.

Cluster Complexes as anti-Werner Complexes†

Abstract: The nomenclature which Alfred Werner introduced in coordination (complex) chemistry is imposed on cluster compounds, especially on those which contain endohedral atoms to enhance the electron count for intra-cluster bonding. Formulae are written in a way that, beginning with the central atom, the sequence of coordination spheres is illustrated. For example, the iodide so far mostly written as Cs4Pr6I13C2, a formula which tells nothing about the structure, is then rewritten as follows, {(C2)Pr6}I13Cs4. Cs2Mo6Cl14 would be [{□Mo6}Cl8iCl6a]Cs2. Square brackets, [ ], are used for an anionic or cationic complex which ideally exists in solution, braces, { }, are reserved for clusters with intra-cluster metal-metal and/or metal-interstitial bonding. Whenever feasible other nomenclatures are included, for example Niggli's way to hint at connections as in {(C2)Dy4/1Dy2/2}2{ODy2/2Dy2/2}2I24, or the Schafer–Schnering nomenclature for ligand functionalities as in {Mo6}Cl8iCl2aCl4/2a-a. This way of considering cluster complexes as anti-Werner complexes is especially useful when coordination numbers and polyhedra of endohedral atoms are considered in a systematic way.

Systematische Studie zu den Koordinationseigenschaften des Guanidin‐Liganden N1,N2‐Bis(1,3‐dimethylimidazolidin‐2‐yliden)‐ethan‐1,2‐diamin mit den Metallen Mn, Co, Ni, Ag und Cu

Abstract: A Systematic Study on the Coordination Properties of the Guanidine Ligand N1,N2-Bis(1,3-dimethylimidazolidin-2-ylidene)-ethane-1,2-diamine with the Metals Mn, Co, Ni, Ag and Cu The syntheses and characterization of the compounds [Mn(DMEG2e)Cl2] (1), [Co(DMEG2e)Cl2] (2), [Ni(DMEG2e)2]I2 (3), [Cu(DMEG2e)I] (4) and {[Ag(DMEG2e)]BF4}n (5) with the bisguanidine ligand N1,N2-bis(1,3-dimethylimidazolidin-2-ylidene)ethane-1,2-diamine (DMEG2e) are described. All complexes are synthesized by the reaction of the corresponding metal salt with the DMEG2e ligand in MeCN or THF. The coordination of the metal atoms vary from a distorted tetrahedron in 1 and 2, a distorted trigonal planar coordination in 4 to linear coordination in 5. Contrasting to the compounds 1, 2, 4 and 5 which exhibit a 1:1 ratio of metal to ligand, two DMEG2e ligands are bound to the Ni atom in the case of 3 resulting in a coordination polyhedron which represents the stage exactly in the middle between the square-planar and the tetrahedral geometry. Whereas crystals of 1, 2, 3 and 4 contain discrete molecules, in 5 the Ag atoms are alternately linked by two different DMEG2e ligands to form a chain structure. The comparative discussion of several DMEG2e containing complexes with the compounds reported herein supplements this systematic study.

1,5‐Diamino‐4‐methyltetrazolium 5‐Nitrotetrazolate – Synthesis, Testing and Scale‐up

Abstract: 1,5-Diamino-4-methyltetrazolium 5-nitrotetrazolate (2b) was synthesized in high yield from 1,5-diamino-4-methyltetrazolium iodide (2a) and highly sensitive silver 5-nitrotetrazolate (AgNT). A safer synthesis, suitable for scale-up, is introduced involving reaction of the previously unreported 1-amino-5-imino-4-methyltetrazole free base (2) with ammonium 5-nitrotetrazolate. Both new compounds (2 and 2b) were fully characterized using vibrational (IR and Raman) and multinuclear NMR spectroscopy (1H, 13C, 14N, 15N), elemental analysis and single crystal X-ray diffraction. The hydrogen-bonding networks of both materials are described in terms of their graph-sets. Compound 2b is hydrolytically stable with a high melting point and concomitant decomposition at 160 °C. The sensitivity of the energetic salt 2b towards impact (>30 J) and friction (>360 N) was tested. The constant volume energy of combustion (ΔcU) of 2b was measured experimentally using bomb calorimetry. In addition, the detonation parameters (detonation pressure and velocity) of the nitrotetrazolate salt were calculated from the energy of formation, the crystal density and the molecular formula using the EXPLO5 computer code (P = 15.5·GPa, D = 6749 m s−1) and are similar to that of TNT and nitroguanidine making 2b of prospective interest in propellant charge formulations or, in combination with a suitable oxidizer, as a solid propellant.

Rietveld Analysis and Raman Spectroscopic Investigations on α-Y2Si2O7

Abstract: Polycrystalline material of α-Y2Si2O7 has been obtained from the thermal decomposition of a precursor prepared by a sol- gel process and subsequently characterized by X-ray powder dif- fraction and Raman spectroscopy. The structure belongs to the so- called B-type of rare earth element disilicates and was refined using the Rietveld method. α-Y2Si2O7 is triclinic with a 6.58620(3), b 6.62895(4), c 12.02723(7) A˚ , α 94.4706(4)°, β 89.0681(4)°, γ 88.2347(4)° ,V 523.166(5) A ˚ 3 , space group P1¯, Z 4a nd Dx 4.39 g/cm 3 . The structure (Rwp 4.7 %, RB 2.9 %) is built from triple tetrahedral (Si3O10)-groups and isolated

Rare Earth Metal‐Rich Magnesium Compounds RE4IrMg (RE = Y, La, Pr, Nd, Sm, Gd, Tb, Dy) and RE23Ir7Mg4 (RE = La, Ce, Pr, Nd)

Abstract: The rare earth metal–rich compounds RE4IrMg (RE = Y, La, Pr, Nd, Sm, Gd, Tb, Dy) and RE23Ir7Mg4 (RE = La, Ce, Pr, Nd) were synthesized from the elements in sealed tantalum tubes in an induction furnace. Several structures were investigated on the basis of X-ray single crystal diffraction: P63mc, Z = 2, a = 1001.2(7), c = 2257.2(5) pm, wR2 = 0.0441, 2402 F2 values, 74 variables for Pr23Ir6.81Mg4, Gd4RhIn type, , Z = 16, a = 1438.3(2) pm, wR2 = 0.0490, 542 F2 values, for La4IrMg, a = 1405.6(2) pm, wR2 = 0.0368, 451 F2 values, for Nd4IrMg, a = 1381.2(2) pm, wR2 = 0.0541, 480 F2 values, for Gd4IrMg, a = 1370.7(2) pm, wR2 = 0.0377, 392 F2 values, for Tb4IrMg with 19 variables per refinement. All other compounds have been characterized by X-ray powder diffraction data. Pr23Ir6.81Mg4 crystallizes with a new structure type. The three crystallographically independent iridium atoms have trigonal prismatic praseodymium coordination with short Ir–Pr distances ranging from 285 to 300 pm. The trigonal prisms are condensed to a three-dimensional network via common edges and corners. Voids in the network are filled by the coordination polyhedra of the Pr4 and Pr6 atoms and Mg4 tetrahedra (312-317 pm Mg–Mg). Similar structural motifs occur in the compounds RE4IrMg, however, with a different connectivity of the building groups. The crystal chemistry of both structure types is comparatively discussed.

Structural and Catalytic Aspects of Dioxomolybdenum(VI) Complexes with ω‐Hydroxy Functionalized N‐Salicylidene Hydrazides

Abstract: The new cis-dioxomolybdenum(VI) complexes [MoO2(salhyhb)]2 (1), [MoO2(salhyhp)] (2), and [MoO2(salhyhh)(MeOH)] (3) with the hydrazone ligands H2salhyhb, Hsalhyhp, and H2salhyhh derived from salicylaldehyde and ω-hydroxy carbonic acid hydrazides with different chain lengths, have been synthesized and spectroscopically characterized. The crystal structures of all three complexes reveal an octahedral environment for the molybdenum atoms with the same basic structural motif. In addition to the two oxo groups an [NO3] donor set is observed which is given by the tridentate Schiff-base ligand and an oxygen atom of a coordinating alcohol. Depending on the side chain length different modes of association are observed. For complex 1 a dimeric structure is obtained, which is linked by coordination of the side chain hydroxy group at the molybdenum atom of the other monomer. The extension of the side chain by one methylene group in complex 2 leads to a polymeric structure, which is based on a similar intermolecular coordination of the side chain hydroxy group. The further increase of the side-chain length in complex 3 results in the coordination of a methanol molecule at the molybdenum atom. For compounds 2 and 3 the additional hydrogen-bonding network leads to the formation of layered structures in the solid state. The synthesized cis-dioxomolybdenum(VI) complexes were tested for their catalytic ability towards the oxidation of sulfides. Although no significant influence of the side chain lengths could be detected, these complexes are efficient catalysts for sulfoxidation.

Metal Derivatives of 1,3‐Imidazolidine‐2‐thione with Divalent d10 Metal Ions (Zn–Hg) : Synthesis and Structures

Abstract: Reactions of divalent Zn-Hg metal ions with 1,3-imidazolidine-2-thione (imdtH2) in 1 : 2 molar ratio have formed monomeric complexes, [Zn(η1-S-imdtH2)2(OAc)2] (1), [Cd((η1-SimdtH2)2I2] (2), [Cd(η1-S-imdtH2)2Br2] (3), and [Hg(η1-S-imdtH2)2I2] (4). Complexes 1–4, have been characterized by elemental analysis (C, H, N), spectroscopy (IR, 1H, NMR) and x-ray crystallography (1-4). Hydrogen bonding between oxygen of acetate and imino hydrogen of ligand, {N(2)–H(2C)···O(2)#} in 1, ring CH and imino hydrogen, {C(2A)–H(2A)···Br(2)#} in 3 have formed H-bonded dimers. Similarly, the interactions between molecular units of complexes 2 and 4 have yielded 2D polymers. The polymerization occurs via intermolecular interactions between thione sulfur and imino hydrogen, {N(2)–H(2)···S(1)#}, imino hydrogen and the iodine atom, {NH(1)···I(2)#} in 2 and imino hydrogen – iodine atom {N(2A)–H(2A)···I(2)} and I···I interaction in 4. Crystal data: [Zn(η1-S-imdtH2)2(OAc)2] (1), C10H18N4O4S2Zn, orthorhombic, Pbcn, a = 9.3854(7) A, b = 12.4647(10) A, c = 13.2263(11) A; V = 1547.3(2) A3, Z = 4, R = 0.0280 [Cd((η1-S-imdtH2)2I2] (2), C6H12CdI2N4S2, orthorhombic, Pnma, a = 13.8487(10) A, b = 14.4232(11) A, c = 7.0659(5) A; Z = 4, V = 1411.36(18) A3, R = 0.0186.

Metal Derivatives of Heterocyclic Thioamides: Synthesis and Crystal Structures of Copper Complexes with 1-Methyl-1,3-imidazoline-2-thione and 1,3-Imidazoline-2-thione

Abstract: Reactions of copper(I) halides (Cl, Br, I) with 1-methyl-1, 3-imidazoline-2-thione (mimzSH) in 1 : 2 molar ratio yielded sulfur-bridged dinuclear [Cu2X2(μ-S-mimzSH)2(η1-S-mimzSH)2] (X = I, 1, Br, 2; Cl, 3) complexes. Copper(I) iodide with 1,3-imidazoline-2-thione (imzSH2) and Ph3P in 1 : 1 : 1 molar ratio has also formed a sulfur-bridged dinuclear [Cu2I2(μ-S-imzSH2)2(PPh3)2] (4) complex. The central Cu(μ-S)2Cu cores form parallelograms with unequal Cu–S bond distances {2.324(2), 2.454(3) A} (1); {2.3118(6), 2.5098(6) A} (2); {2.3075(4), 2.5218(4) A} (3); {2.3711(8), 2.4473(8) A} (4). The Cu···Cu separations, 2.759–2.877A in complexes 1–3 are much shorter than 3.3446A in complex 4. The weak intermolecular interactions {H2CH···S# (2); CH···Cl# (3); NH···I# (4)} between dimeric units in complexes 2–4 lead to the formation of linear 1D polymers.

Structural Phase Transitions in Ag2Se (Naumannite)

Abstract: Ag2Se (naumannite) was investigated by means of temperature dependent synchrotron powder diffraction and DTA. Upon heating in air the known 1st order phase transition from orthorhombic low-temperature Ag2Se (P212121, Z = 4) to cubic ion conducting high-temperature Ag2Se (Im3m, Z = 2) was observed at approx. 140 °C. Upon cooling a small hysteresis was detected (TPU = 120 °C). It was found that when heated in air Ag2Se segregates elemental selenium. After cooling to ambient temperature the resulting low-temperature Ag2Se can no longer be described in the known structural model with harmonic terms, the use of anharmonic terms is probably necessary. The phase transition and the segregation of selenium are accompanied by an increased crystallinity of the sample, as the halfwidths of the reflections become significantly smaller. Approaching the phase transition the lattice parameters of orthorhombic Ag2Se show a distinct anisotropic behaviour: b and c show a positive and a a negative thermal expansion. When heated in argon the segregation of selenium is not observed.

The Influence of Substituents at C2 Carbon Atom of Thiosemicarbazones {R(H)C2=N3‐N2(H)‐C1(=S)‐N1H2} on their Dentacy in PtII/PdII Complexes: Synthesis, Spectroscopy, and Crystal Structures

Abstract: The coordination chemistry of platinum(II) with a series of thiosemicarbazones {R(H)C2=N3-N2(H)-C1(=S)-N1H2, R = 2-hydroxyphenyl, H2stsc; pyrrole, H2ptsc; phenyl, Hbtsc} is described. Reactions of trans-PtCl2(PPh3)2 precursor with H2stsc (or H2ptsc) in 1 : 1 molar ratio in the presence of Et3N base yielded complexes, [Pt(η3- O, N3, S-stsc)(PPh3)] (1) and [Pt(η3- N4, N3, S-ptsc)(PPh3)] (2), respectively. Further, trans-PtCl2(PPh3)2 and Hbtsc in 1 : 2 (M : L) molar ratio yielded a different compound, [Pt(η2- N3, S-btsc)(η1-S-btsc)(PPh3)] (3). Complex 1 involved deprotonation of hydrazinic (-N2H-) and hydroxyl (-OH) groups, and stsc2− is coordinating via O, N3, S donor atoms, while complex 2 involved deprotonation of hydrazinic (-N2H-) and -N4H groups and ptsc2− is probably coordinating via N4, N3, S donor atoms. Reaction of PdCl2(PPh3)2 with Hbtsc-Me {C6H5(CH3)C2=N3-N2(H)-C1(=S)-N1H2} yielded a cyclometallated complex [Pd(η3-C, N3, S-btsc-Me)(PPh3)] (4). These complexes have been characterized with the help of analytical data, spectroscopic techniques {IR, NMR (1H, 31P), U.V} and single crystal X-ray crystallography (1, 3 and 4). The effects of substituents at C2 carbon of thiosemicarbazones on their dentacy and cyclometallation are emphasized.

Die Kristallstruktur von [BeCl2(15‐Krone‐5)]

Abstract: Crystal Structure of [BeCl2(15-Crown-5)] Single crystals of [BeCl2(15-crown-5)] (1) were obtained from dichloromethane solutions of BeCl2 in the presence of the equivalent amount of 15-crown-5 and characterized by IR spectroscopy and X-ray diffraction. Space group P21/c, Z = 4, lattice dimensions at 100 K: a = 1036.2(1), b = 1071.1(1), c = 1360.1(1) pm, β = 109.86(1)°, R1 = 0.0225. The structure determination shows no disorder, all hydrogen positions were refined isotropically. The results are in contrast to the previously reported crystal structure determination in the space group P21nb. The beryllium atom of 1 forms a BeO2C2 five-membered heterocycle with terminal chlorine atoms to give a distorted tetrahedral coordination with distances Be–O 166.5(2), 169.9(2) pm, and Be–Cl 195.8(2), 197.8(2) pm. The structural results are in good agreement with DFT calculations on B3LYP/6-311+G** level.